Thread Subject: teitac-telecom, PSTN Reference

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From: Jasionowski, Tony
Date: Mon, Mar 26 2007 6:55 AM
Subject: teitac-telecom, PSTN Reference

Paul,
"wired analog and wired non-IP digital" seems odd considering we also
have "cordless analog and digital". I suggest we stick with PSTN for now
unless someone can propose acceptable alternative term. FYI, anyone can
easily find the definition of PSTN at several web sites including:
http://dictionary.reference.com/browse/pstn
Therefore, PSTN may not be so confusing after all.
Tony Jasionowski
Panasonic


Message: 1
Date: Sat, 24 Mar 2007 17:41:44 -0600
From: "Michaelis, Paul R. (Paul)" < = EMAIL ADDRESS REMOVED = >
Subject: Re: [teitac-telecom] Telecommunications Working Group- Draft
1 Template for 508 in WORD
To: "TEITAC Telecommunications Subcommittee"
< = EMAIL ADDRESS REMOVED = >
Cc: = EMAIL ADDRESS REMOVED = , Creagan Tim
< = EMAIL ADDRESS REMOVED = >
Message-ID:

< = EMAIL ADDRESS REMOVED = >

Content-Type: text/plain; charset="us-ascii"

Regarding the reference to "PSTN" versus "IP" in many of the proposed
requirements, I agree that IP telephones should be treated differently
but am concerned that describing the non-IP systems as "PSTN" will
create a lot of confusion.



The "PSTN" is the Public Switched Telephone Network. If asked to
describe a PSTN telephony endpoint, I imagine that most telecom
specialists would say it was an analog device that complies with the FCC
regulations that govern residential telephones. If we use this
definition, I can't remember the last time I've seen a government
procurement of telecom equipment that falls into this category.



There are at least three different categories of non-IP wired telephones
in common use today:



Residential analog. (This is what most folks would classify as a "PSTN
phone.")



Enterprise analog. (The distinction between these phones and
residential analog sets is that the enterprise sets connect to the PSTN
via a PBX or switch that is owned by the enterprise. An important
electrical distinction is that, unlike enterprise analog telephones,
residential telephones are required to do "automatic loop length
compensation" to account for distance-related differences in electrical
resistance and capacitance in the line between the phone and the
associated central office. Another important distinction is that many
enterprise analog solutions are actually hybrid analog/digital sets.
The audio stream is carried as traditional analog, supplemented by
digital signaling that, for example, controls the phone's display.)



Enterprise digital. (This is what is purchased in the vast majority of
non-IP wired telephony procurements by the government. All audio
transmissions entering or leaving the phone are digitally encoded,
typically using the G.711 algorithm that I described in a previous
message. Signaling and call control is also digital, typically using
protocols that are proprietary to the individual manufacturers.)



Wired residential analog systems, wired enterprise analog systems, and
wired enterprise digital systems are able to transmit Baudot TTY signals
with 100% reliability. IP telephony is different.



Depending on network characteristics, the mechanisms that are used in
order to transport voice signals within IP networks are not always
suitable for transporting Baudot TTY tones. Common sources of
impairment include packet loss and the use of voice-optimized audio
compression algorithms, such as G.729. For this reason, a traditional
TTY device used in conjunction with an IP phone (for example, via an
acoustic coupler) is not always going to be reliable.



The good news is that, although not yet in common use, there are
international standards that describe how to transport text and Baudot
tones reliably on IP networks. In general, these techniques do not use
the same audio encoding and transmission mechanisms that are used for
voice. I agree completely that the availability of these techniques,
coupled with the inherent unreliability of Baudot TTY transmissions via
the "voice channels" of IP telephone networks, makes it essential that
we treat IP telephony as a special case in the Section 508 refresh.



Getting back to the original topic of my message... We need a term
other than PSTN to describe non-IP wired telephony. Ideally, it should
be a term or description that would make sense to someone who is not
knowledgeable about telephone engineering. To start the ball rolling, I
suggest "wired analog and wired non-IP digital" as a substitute for
PSTN. (I deliberately use the word "wired" because wireless devices
have special characteristics that may need to be addressed separately.)



-- Paul Michaelis

From: Michaelis, Paul R. (Paul)
Date: Mon, Mar 26 2007 8:30 AM
Subject: Re: teitac-telecom, PSTN Reference

Tony,

Quoting from the web page you cited:

"Public Switched Telephone Network communications
(PSTN, T.70) The collection of interconnected systems operated by the
various telephone companies and administrations (telcos and PTTs) around
the world. Also known as the Plain Old Telephone System (POTS) in
contrast to xDSL and ISDN (not to mention other forms of PANS)."

Note that this definition seems to say that services such as ISDN are
*not* considered to be PSTN. Presumably, this would also mean that
digital telephones, operating behind a PBX, are not PSTN. These phones
are not IP either. This would mean that the proposal to classify
equipment as either PSTN or IP will leave an entire category of telecom
equipment without an obvious home.

A reason why I am passionate about this issue is that I've wasted a
tremendous amount of time over the past seven years, arguing with people
-- including people in my own company -- about how to interpret the
Section 508 requirements. "This requirement means this!" "No, it means
that!!!" As part of the Section 508 refresh, we need to write
unambiguous requirements that cannot be misinterpreted. Without that,
contract officers will continue to buy whatever the heck they want,
manufacturers will continue to sell inaccessible solutions to the
government, and the likelihood that my company will let me build
anything else will be close to nil.

Getting back to the use of "PSTN" to describe non-IP phones, my fear is
that some people who are looking for an excuse to avoid investing in
accessibility -- including people in my own company -- will claim that
ISDN and digital phones behind a PBX are exempt because they don't fall
into either category. During the next seven years, I want to spend more
time building solutions, and less time arguing about whether they ought
to be built.

-- Paul Michaelis




-----Original Message-----
From: Jasionowski, Tony [mailto: = EMAIL ADDRESS REMOVED = ]
Sent: Monday, March 26, 2007 7:42 AM
To: = EMAIL ADDRESS REMOVED =
Subject: [teitac-telecom] teitac-telecom, PSTN Reference

Paul,
"wired analog and wired non-IP digital" seems odd considering we also
have "cordless analog and digital". I suggest we stick with PSTN for now
unless someone can propose acceptable alternative term. FYI, anyone can
easily find the definition of PSTN at several web sites including:
http://dictionary.reference.com/browse/pstn
Therefore, PSTN may not be so confusing after all.
Tony Jasionowski
Panasonic


Message: 1
Date: Sat, 24 Mar 2007 17:41:44 -0600
From: "Michaelis, Paul R. (Paul)" < = EMAIL ADDRESS REMOVED = >
Subject: Re: [teitac-telecom] Telecommunications Working Group- Draft
1 Template for 508 in WORD
To: "TEITAC Telecommunications Subcommittee"
< = EMAIL ADDRESS REMOVED = >
Cc: = EMAIL ADDRESS REMOVED = , Creagan Tim
< = EMAIL ADDRESS REMOVED = >
Message-ID:

< = EMAIL ADDRESS REMOVED = >

Content-Type: text/plain; charset="us-ascii"

Regarding the reference to "PSTN" versus "IP" in many of the proposed
requirements, I agree that IP telephones should be treated differently
but am concerned that describing the non-IP systems as "PSTN" will
create a lot of confusion.



The "PSTN" is the Public Switched Telephone Network. If asked to
describe a PSTN telephony endpoint, I imagine that most telecom
specialists would say it was an analog device that complies with the FCC
regulations that govern residential telephones. If we use this
definition, I can't remember the last time I've seen a government
procurement of telecom equipment that falls into this category.



There are at least three different categories of non-IP wired telephones
in common use today:



Residential analog. (This is what most folks would classify as a "PSTN
phone.")



Enterprise analog. (The distinction between these phones and
residential analog sets is that the enterprise sets connect to the PSTN
via a PBX or switch that is owned by the enterprise. An important
electrical distinction is that, unlike enterprise analog telephones,
residential telephones are required to do "automatic loop length
compensation" to account for distance-related differences in electrical
resistance and capacitance in the line between the phone and the
associated central office. Another important distinction is that many
enterprise analog solutions are actually hybrid analog/digital sets.
The audio stream is carried as traditional analog, supplemented by
digital signaling that, for example, controls the phone's display.)



Enterprise digital. (This is what is purchased in the vast majority of
non-IP wired telephony procurements by the government. All audio
transmissions entering or leaving the phone are digitally encoded,
typically using the G.711 algorithm that I described in a previous
message. Signaling and call control is also digital, typically using
protocols that are proprietary to the individual manufacturers.)



Wired residential analog systems, wired enterprise analog systems, and
wired enterprise digital systems are able to transmit Baudot TTY signals
with 100% reliability. IP telephony is different.



Depending on network characteristics, the mechanisms that are used in
order to transport voice signals within IP networks are not always
suitable for transporting Baudot TTY tones. Common sources of
impairment include packet loss and the use of voice-optimized audio
compression algorithms, such as G.729. For this reason, a traditional
TTY device used in conjunction with an IP phone (for example, via an
acoustic coupler) is not always going to be reliable.



The good news is that, although not yet in common use, there are
international standards that describe how to transport text and Baudot
tones reliably on IP networks. In general, these techniques do not use
the same audio encoding and transmission mechanisms that are used for
voice. I agree completely that the availability of these techniques,
coupled with the inherent unreliability of Baudot TTY transmissions via
the "voice channels" of IP telephone networks, makes it essential that
we treat IP telephony as a special case in the Section 508 refresh.



Getting back to the original topic of my message... We need a term
other than PSTN to describe non-IP wired telephony. Ideally, it should
be a term or description that would make sense to someone who is not
knowledgeable about telephone engineering. To start the ball rolling, I
suggest "wired analog and wired non-IP digital" as a substitute for
PSTN. (I deliberately use the word "wired" because wireless devices
have special characteristics that may need to be addressed separately.)



-- Paul Michaelis

From: Jasionowski, Tony
Date: Mon, Mar 26 2007 11:25 AM
Subject: teitac-telecom, PSTN Reference

Paul,
Noted, PSTN is also not acceptable for the reasons you passionately
mention, therefore, I will investigate other suitable alternatives.
Tony Jasionowski
Panasonic
----------------------------------------------------------------------

Message: 1
Date: Mon, 26 Mar 2007 09:28:09 -0600
From: "Michaelis, Paul R. (Paul)" < = EMAIL ADDRESS REMOVED = >
Subject: Re: [teitac-telecom] teitac-telecom, PSTN Reference
To: "TEITAC Telecommunications Subcommittee"
< = EMAIL ADDRESS REMOVED = >
Message-ID:

< = EMAIL ADDRESS REMOVED = >

Content-Type: text/plain; charset="us-ascii"

Tony,

Quoting from the web page you cited:

"Public Switched Telephone Network communications (PSTN, T.70) The
collection of interconnected systems operated by the various telephone
companies and administrations (telcos and PTTs) around the world. Also
known as the Plain Old Telephone System (POTS) in contrast to xDSL and
ISDN (not to mention other forms of PANS)."

Note that this definition seems to say that services such as ISDN are
*not* considered to be PSTN. Presumably, this would also mean that
digital telephones, operating behind a PBX, are not PSTN. These phones
are not IP either. This would mean that the proposal to classify
equipment as either PSTN or IP will leave an entire category of telecom
equipment without an obvious home.

A reason why I am passionate about this issue is that I've wasted a
tremendous amount of time over the past seven years, arguing with people
-- including people in my own company -- about how to interpret the
Section 508 requirements. "This requirement means this!" "No, it means
that!!!" As part of the Section 508 refresh, we need to write
unambiguous requirements that cannot be misinterpreted. Without that,
contract officers will continue to buy whatever the heck they want,
manufacturers will continue to sell inaccessible solutions to the
government, and the likelihood that my company will let me build
anything else will be close to nil.

Getting back to the use of "PSTN" to describe non-IP phones, my fear is
that some people who are looking for an excuse to avoid investing in
accessibility -- including people in my own company -- will claim that
ISDN and digital phones behind a PBX are exempt because they don't fall
into either category. During the next seven years, I want to spend more
time building solutions, and less time arguing about whether they ought
to be built.

-- Paul Michaelis




-----Original Message-----
From: Jasionowski, Tony [mailto: = EMAIL ADDRESS REMOVED = ]
Sent: Monday, March 26, 2007 7:42 AM
To: = EMAIL ADDRESS REMOVED =
Subject: [teitac-telecom] teitac-telecom, PSTN Reference

Paul,
"wired analog and wired non-IP digital" seems odd considering we also
have "cordless analog and digital". I suggest we stick with PSTN for now
unless someone can propose acceptable alternative term. FYI, anyone can
easily find the definition of PSTN at several web sites including:
http://dictionary.reference.com/browse/pstn
Therefore, PSTN may not be so confusing after all.
Tony Jasionowski
Panasonic


Message: 1
Date: Sat, 24 Mar 2007 17:41:44 -0600
From: "Michaelis, Paul R. (Paul)" < = EMAIL ADDRESS REMOVED = >
Subject: Re: [teitac-telecom] Telecommunications Working Group- Draft
1 Template for 508 in WORD
To: "TEITAC Telecommunications Subcommittee"
< = EMAIL ADDRESS REMOVED = >
Cc: = EMAIL ADDRESS REMOVED = , Creagan Tim
< = EMAIL ADDRESS REMOVED = >
Message-ID:

< = EMAIL ADDRESS REMOVED = >

Content-Type: text/plain; charset="us-ascii"

Regarding the reference to "PSTN" versus "IP" in many of the proposed
requirements, I agree that IP telephones should be treated differently
but am concerned that describing the non-IP systems as "PSTN" will
create a lot of confusion.



The "PSTN" is the Public Switched Telephone Network. If asked to
describe a PSTN telephony endpoint, I imagine that most telecom
specialists would say it was an analog device that complies with the FCC
regulations that govern residential telephones. If we use this
definition, I can't remember the last time I've seen a government
procurement of telecom equipment that falls into this category.



There are at least three different categories of non-IP wired telephones
in common use today:



Residential analog. (This is what most folks would classify as a "PSTN
phone.")



Enterprise analog. (The distinction between these phones and
residential analog sets is that the enterprise sets connect to the PSTN
via a PBX or switch that is owned by the enterprise. An important
electrical distinction is that, unlike enterprise analog telephones,
residential telephones are required to do "automatic loop length
compensation" to account for distance-related differences in electrical
resistance and capacitance in the line between the phone and the
associated central office. Another important distinction is that many
enterprise analog solutions are actually hybrid analog/digital sets.
The audio stream is carried as traditional analog, supplemented by
digital signaling that, for example, controls the phone's display.)



Enterprise digital. (This is what is purchased in the vast majority of
non-IP wired telephony procurements by the government. All audio
transmissions entering or leaving the phone are digitally encoded,
typically using the G.711 algorithm that I described in a previous
message. Signaling and call control is also digital, typically using
protocols that are proprietary to the individual manufacturers.)



Wired residential analog systems, wired enterprise analog systems, and
wired enterprise digital systems are able to transmit Baudot TTY signals
with 100% reliability. IP telephony is different.



Depending on network characteristics, the mechanisms that are used in
order to transport voice signals within IP networks are not always
suitable for transporting Baudot TTY tones. Common sources of
impairment include packet loss and the use of voice-optimized audio
compression algorithms, such as G.729. For this reason, a traditional
TTY device used in conjunction with an IP phone (for example, via an
acoustic coupler) is not always going to be reliable.



The good news is that, although not yet in common use, there are
international standards that describe how to transport text and Baudot
tones reliably on IP networks. In general, these techniques do not use
the same audio encoding and transmission mechanisms that are used for
voice. I agree completely that the availability of these techniques,
coupled with the inherent unreliability of Baudot TTY transmissions via
the "voice channels" of IP telephone networks, makes it essential that
we treat IP telephony as a special case in the Section 508 refresh.



Getting back to the original topic of my message... We need a term
other than PSTN to describe non-IP wired telephony. Ideally, it should
be a term or description that would make sense to someone who is not
knowledgeable about telephone engineering. To start the ball rolling, I
suggest "wired analog and wired non-IP digital" as a substitute for
PSTN. (I deliberately use the word "wired" because wireless devices
have special characteristics that may need to be addressed separately.)



-- Paul Michaelis

From: Gregg Vanderheiden
Date: Fri, Mar 30 2007 8:50 AM
Subject: Re: teitac-telecom, PSTN Reference

Good post.



It is important however to note that the world is not divided into PSTN and
IP.





I would suggest that we think of Telecom in 3 categories



1) Public Analog phone systems (PSTN)

- Characteristics

- only 1 channel which is for voice

- can't transmit data except as tones



2) Public IP/SIP phone system (emerging - SIP / IP)

- public IP Phone network

- Characteristics

- currently just uses the Internet (for
public system. Other networks are used for private.)

- shouldn't be transmitting data via tones.
Data (including text) can and should be transmitted as data.

- supports multiple parallel channels in
both directions (voice, text, and video)



3) All other non-public phone systems that either do or do not connect
to the public system(s)

Some examples of #3 would include

- Cellular phone systems (the link from phone to PSTN only)

- Skype

- phone systems run by Cable Companies (from house to PSTN or
IP/SIP only)

- PBXs





WHY DIVIDED IN THREE



I divide it into these three because they have very different
characteristics and need different rules.

- what works in 1 won't work well in 2.

- What works in 2 doesn't work in 1.

So the requirements must be different between these two.



#3 is internal and controlled by each system. Also use a wide variety of
different technologies.

- shouldn't regulate these except where they interface with users or the
public systems

- internally, we should keep hands off for HOW. Just talk
about what they should be capable of.

- So we should say WHAT they (#3 technologies) should do but NOT HOW they
should do it.



#1 and #2 however are not controlled by any one party.

o They are not even controlled by any one industry.

o So we need to specify not only WHAT but ALSO HOW they implement
some things or there will be no interoperability.

o They can do other things in ADDITION to the required formats. But
they MUST support the required format or there is no guarantee of
interoperability. And market forces cannot enforce or cause
interoperability as has been so often shown.





Gregg

-- ------------------------------

Gregg C Vanderheiden Ph.D.







> -----Original Message-----

> From: = EMAIL ADDRESS REMOVED =

> [mailto: = EMAIL ADDRESS REMOVED = ] On Behalf Of

> Michaelis, Paul R. (Paul)

> Sent: Monday, March 26, 2007 10:28 AM

> To: TEITAC Telecommunications Subcommittee

> Subject: Re: [teitac-telecom] teitac-telecom, PSTN Reference

>

> Tony,

>

> Quoting from the web page you cited:

>

> "Public Switched Telephone Network communications (PSTN,

> T.70) The collection of interconnected systems operated by

> the various telephone companies and administrations (telcos

> and PTTs) around the world. Also known as the Plain Old

> Telephone System (POTS) in contrast to xDSL and ISDN (not to

> mention other forms of PANS)."

>

> Note that this definition seems to say that services such as ISDN are

> *not* considered to be PSTN. Presumably, this would also

> mean that digital telephones, operating behind a PBX, are not

> PSTN. These phones are not IP either. This would mean that

> the proposal to classify equipment as either PSTN or IP will

> leave an entire category of telecom equipment without an obvious home.

>

> A reason why I am passionate about this issue is that I've

> wasted a tremendous amount of time over the past seven years,

> arguing with people

> -- including people in my own company -- about how to

> interpret the Section 508 requirements. "This requirement

> means this!" "No, it means that!!!" As part of the Section

> 508 refresh, we need to write unambiguous requirements that

> cannot be misinterpreted. Without that, contract officers

> will continue to buy whatever the heck they want,

> manufacturers will continue to sell inaccessible solutions to

> the government, and the likelihood that my company will let

> me build anything else will be close to nil.

>

> Getting back to the use of "PSTN" to describe non-IP phones,

> my fear is that some people who are looking for an excuse to

> avoid investing in accessibility -- including people in my

> own company -- will claim that ISDN and digital phones behind

> a PBX are exempt because they don't fall into either

> category. During the next seven years, I want to spend more

> time building solutions, and less time arguing about whether

> they ought to be built.

>

> -- Paul Michaelis

>

>

>

>

> -----Original Message-----

> From: Jasionowski, Tony [mailto: = EMAIL ADDRESS REMOVED = ]

> Sent: Monday, March 26, 2007 7:42 AM

> To: = EMAIL ADDRESS REMOVED =

> Subject: [teitac-telecom] teitac-telecom, PSTN Reference

>

> Paul,

> "wired analog and wired non-IP digital" seems odd considering

> we also have "cordless analog and digital". I suggest we

> stick with PSTN for now unless someone can propose acceptable

> alternative term. FYI, anyone can easily find the definition

> of PSTN at several web sites including:

> http://dictionary.reference.com/browse/pstn

> Therefore, PSTN may not be so confusing after all.

> Tony Jasionowski

> Panasonic

>

>

> Message: 1

> Date: Sat, 24 Mar 2007 17:41:44 -0600

> From: "Michaelis, Paul R. (Paul)" < = EMAIL ADDRESS REMOVED = >

> Subject: Re: [teitac-telecom] Telecommunications Working Group- Draft

> 1 Template for 508 in WORD

> To: "TEITAC Telecommunications Subcommittee"

> < = EMAIL ADDRESS REMOVED = >

> Cc: = EMAIL ADDRESS REMOVED = , Creagan Tim

> < = EMAIL ADDRESS REMOVED = >

> Message-ID:

>

> < = EMAIL ADDRESS REMOVED = .

> avaya.com>

>

> Content-Type: text/plain; charset="us-ascii"

>

> Regarding the reference to "PSTN" versus "IP" in many of the

> proposed requirements, I agree that IP telephones should be

> treated differently but am concerned that describing the

> non-IP systems as "PSTN" will create a lot of confusion.

>

>

>

> The "PSTN" is the Public Switched Telephone Network. If

> asked to describe a PSTN telephony endpoint, I imagine that

> most telecom specialists would say it was an analog device

> that complies with the FCC regulations that govern

> residential telephones. If we use this definition, I can't

> remember the last time I've seen a government procurement of

> telecom equipment that falls into this category.

>

>

>

> There are at least three different categories of non-IP wired

> telephones in common use today:

>

>

>

> Residential analog. (This is what most folks would classify

> as a "PSTN

> phone.")

>

>

>

> Enterprise analog. (The distinction between these phones and

> residential analog sets is that the enterprise sets connect

> to the PSTN via a PBX or switch that is owned by the

> enterprise. An important electrical distinction is that,

> unlike enterprise analog telephones, residential telephones

> are required to do "automatic loop length compensation" to

> account for distance-related differences in electrical

> resistance and capacitance in the line between the phone and

> the associated central office. Another important distinction

> is that many enterprise analog solutions are actually hybrid

> analog/digital sets.

> The audio stream is carried as traditional analog,

> supplemented by digital signaling that, for example, controls

> the phone's display.)

>

>

>

> Enterprise digital. (This is what is purchased in the vast

> majority of non-IP wired telephony procurements by the

> government. All audio transmissions entering or leaving the

> phone are digitally encoded, typically using the G.711

> algorithm that I described in a previous message. Signaling

> and call control is also digital, typically using protocols

> that are proprietary to the individual manufacturers.)

>

>

>

> Wired residential analog systems, wired enterprise analog

> systems, and wired enterprise digital systems are able to

> transmit Baudot TTY signals with 100% reliability. IP

> telephony is different.

>

>

>

> Depending on network characteristics, the mechanisms that are

> used in order to transport voice signals within IP networks

> are not always suitable for transporting Baudot TTY tones.

> Common sources of impairment include packet loss and the use

> of voice-optimized audio compression algorithms, such as

> G.729. For this reason, a traditional TTY device used in

> conjunction with an IP phone (for example, via an acoustic

> coupler) is not always going to be reliable.

>

>

>

> The good news is that, although not yet in common use, there

> are international standards that describe how to transport

> text and Baudot tones reliably on IP networks. In general,

> these techniques do not use the same audio encoding and

> transmission mechanisms that are used for voice. I agree

> completely that the availability of these techniques, coupled

> with the inherent unreliability of Baudot TTY transmissions

> via the "voice channels" of IP telephone networks, makes it

> essential that we treat IP telephony as a special case in the

> Section 508 refresh.

>

>

>

> Getting back to the original topic of my message... We need

> a term other than PSTN to describe non-IP wired telephony.

> Ideally, it should be a term or description that would make

> sense to someone who is not knowledgeable about telephone

> engineering. To start the ball rolling, I suggest "wired

> analog and wired non-IP digital" as a substitute for PSTN.

> (I deliberately use the word "wired" because wireless devices

> have special characteristics that may need to be addressed

> separately.)

>

>

>

> -- Paul Michaelis

>

>

>

>

>

>

>

>

From: Gregg Vanderheiden
Date: Sat, Mar 31 2007 12:55 PM
Subject: Re: teitac-telecom, PSTN Reference

See previous post.

We only need to talk about the public phone systems. (The PSTN and IP)

For other systems - we should treat them as proprietary and keep our hands
off until they meet with the public systems. At that time they would need
to be in the common public format.

There are too many non-public technologies and it would not be possible or
appropriate to specify what form they should use internally.



I think the Two Tier approach may be appropriate though.


A general guideline (that is testable)
- under it the specific testable guidelines where they are appropriate
- (sufficient techniques would not be in the guidelines but in support docs
from Access Board.


Gregg
-- ------------------------------
Gregg C Vanderheiden Ph.D.


> -----Original Message-----
> From: = EMAIL ADDRESS REMOVED = [mailto:teitac-telecom-
> = EMAIL ADDRESS REMOVED = ] On Behalf Of Jasionowski, Tony
> Sent: Monday, March 26, 2007 1:17 PM
> To: = EMAIL ADDRESS REMOVED =
> Subject: [teitac-telecom] teitac-telecom, PSTN Reference
>
> Paul,
> Noted, PSTN is also not acceptable for the reasons you passionately
> mention, therefore, I will investigate other suitable alternatives.
> Tony Jasionowski
> Panasonic
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Mon, 26 Mar 2007 09:28:09 -0600
> From: "Michaelis, Paul R. (Paul)" < = EMAIL ADDRESS REMOVED = >
> Subject: Re: [teitac-telecom] teitac-telecom, PSTN Reference
> To: "TEITAC Telecommunications Subcommittee"
> < = EMAIL ADDRESS REMOVED = >
> Message-ID:
>
> < = EMAIL ADDRESS REMOVED = >
>
> Content-Type: text/plain; charset="us-ascii"
>
> Tony,
>
> Quoting from the web page you cited:
>
> "Public Switched Telephone Network communications (PSTN, T.70) The
> collection of interconnected systems operated by the various telephone
> companies and administrations (telcos and PTTs) around the world. Also
> known as the Plain Old Telephone System (POTS) in contrast to xDSL and
> ISDN (not to mention other forms of PANS)."
>
> Note that this definition seems to say that services such as ISDN are
> *not* considered to be PSTN. Presumably, this would also mean that
> digital telephones, operating behind a PBX, are not PSTN. These phones
> are not IP either. This would mean that the proposal to classify
> equipment as either PSTN or IP will leave an entire category of telecom
> equipment without an obvious home.
>
> A reason why I am passionate about this issue is that I've wasted a
> tremendous amount of time over the past seven years, arguing with people
> -- including people in my own company -- about how to interpret the
> Section 508 requirements. "This requirement means this!" "No, it means
> that!!!" As part of the Section 508 refresh, we need to write
> unambiguous requirements that cannot be misinterpreted. Without that,
> contract officers will continue to buy whatever the heck they want,
> manufacturers will continue to sell inaccessible solutions to the
> government, and the likelihood that my company will let me build
> anything else will be close to nil.
>
> Getting back to the use of "PSTN" to describe non-IP phones, my fear is
> that some people who are looking for an excuse to avoid investing in
> accessibility -- including people in my own company -- will claim that
> ISDN and digital phones behind a PBX are exempt because they don't fall
> into either category. During the next seven years, I want to spend more
> time building solutions, and less time arguing about whether they ought
> to be built.
>
> -- Paul Michaelis
>
>
>
>
> -----Original Message-----
> From: Jasionowski, Tony [mailto: = EMAIL ADDRESS REMOVED = ]
> Sent: Monday, March 26, 2007 7:42 AM
> To: = EMAIL ADDRESS REMOVED =
> Subject: [teitac-telecom] teitac-telecom, PSTN Reference
>
> Paul,
> "wired analog and wired non-IP digital" seems odd considering we also
> have "cordless analog and digital". I suggest we stick with PSTN for now
> unless someone can propose acceptable alternative term. FYI, anyone can
> easily find the definition of PSTN at several web sites including:
> http://dictionary.reference.com/browse/pstn
> Therefore, PSTN may not be so confusing after all.
> Tony Jasionowski
> Panasonic
>
>
> Message: 1
> Date: Sat, 24 Mar 2007 17:41:44 -0600
> From: "Michaelis, Paul R. (Paul)" < = EMAIL ADDRESS REMOVED = >
> Subject: Re: [teitac-telecom] Telecommunications Working Group- Draft
> 1 Template for 508 in WORD
> To: "TEITAC Telecommunications Subcommittee"
> < = EMAIL ADDRESS REMOVED = >
> Cc: = EMAIL ADDRESS REMOVED = , Creagan Tim
> < = EMAIL ADDRESS REMOVED = >
> Message-ID:
>
> < = EMAIL ADDRESS REMOVED = >
>
> Content-Type: text/plain; charset="us-ascii"
>
> Regarding the reference to "PSTN" versus "IP" in many of the proposed
> requirements, I agree that IP telephones should be treated differently
> but am concerned that describing the non-IP systems as "PSTN" will
> create a lot of confusion.
>
>
>
> The "PSTN" is the Public Switched Telephone Network. If asked to
> describe a PSTN telephony endpoint, I imagine that most telecom
> specialists would say it was an analog device that complies with the FCC
> regulations that govern residential telephones. If we use this
> definition, I can't remember the last time I've seen a government
> procurement of telecom equipment that falls into this category.
>
>
>
> There are at least three different categories of non-IP wired telephones
> in common use today:
>
>
>
> Residential analog. (This is what most folks would classify as a "PSTN
> phone.")
>
>
>
> Enterprise analog. (The distinction between these phones and
> residential analog sets is that the enterprise sets connect to the PSTN
> via a PBX or switch that is owned by the enterprise. An important
> electrical distinction is that, unlike enterprise analog telephones,
> residential telephones are required to do "automatic loop length
> compensation" to account for distance-related differences in electrical
> resistance and capacitance in the line between the phone and the
> associated central office. Another important distinction is that many
> enterprise analog solutions are actually hybrid analog/digital sets.
> The audio stream is carried as traditional analog, supplemented by
> digital signaling that, for example, controls the phone's display.)
>
>
>
> Enterprise digital. (This is what is purchased in the vast majority of
> non-IP wired telephony procurements by the government. All audio
> transmissions entering or leaving the phone are digitally encoded,
> typically using the G.711 algorithm that I described in a previous
> message. Signaling and call control is also digital, typically using
> protocols that are proprietary to the individual manufacturers.)
>
>
>
> Wired residential analog systems, wired enterprise analog systems, and
> wired enterprise digital systems are able to transmit Baudot TTY signals
> with 100% reliability. IP telephony is different.
>
>
>
> Depending on network characteristics, the mechanisms that are used in
> order to transport voice signals within IP networks are not always
> suitable for transporting Baudot TTY tones. Common sources of
> impairment include packet loss and the use of voice-optimized audio
> compression algorithms, such as G.729. For this reason, a traditional
> TTY device used in conjunction with an IP phone (for example, via an
> acoustic coupler) is not always going to be reliable.
>
>
>
> The good news is that, although not yet in common use, there are
> international standards that describe how to transport text and Baudot
> tones reliably on IP networks. In general, these techniques do not use
> the same audio encoding and transmission mechanisms that are used for
> voice. I agree completely that the availability of these techniques,
> coupled with the inherent unreliability of Baudot TTY transmissions via
> the "voice channels" of IP telephone networks, makes it essential that
> we treat IP telephony as a special case in the Section 508 refresh.
>
>
>
> Getting back to the original topic of my message... We need a term
> other than PSTN to describe non-IP wired telephony. Ideally, it should
> be a term or description that would make sense to someone who is not
> knowledgeable about telephone engineering. To start the ball rolling, I
> suggest "wired analog and wired non-IP digital" as a substitute for
> PSTN. (I deliberately use the word "wired" because wireless devices
> have special characteristics that may need to be addressed separately.)
>
>
>
> -- Paul Michaelis
>
>
>
>
>
>
>

From: Tom Brett
Date: Sat, Mar 31 2007 3:10 PM
Subject: Re: teitac-telecom, PSTN Reference

How would a public phone system be defined?

I am not sure it can be said that all government telecommunication systems
fall into a PSTN or IP classification. If the government is using something
other than a PSTN or IP system it would need to be considered public.

Tom Brett


-----Original Message-----
From: = EMAIL ADDRESS REMOVED =
[mailto: = EMAIL ADDRESS REMOVED = ] On Behalf Of Gregg
Vanderheiden
Sent: Saturday, March 31, 2007 3:52 PM
To: 'TEITAC Telecommunications Subcommittee'
Subject: Re: [teitac-telecom] teitac-telecom, PSTN Reference

See previous post.

We only need to talk about the public phone systems. (The PSTN and IP)

For other systems - we should treat them as proprietary and keep our hands
off until they meet with the public systems. At that time they would need
to be in the common public format.

There are too many non-public technologies and it would not be possible or
appropriate to specify what form they should use internally.



I think the Two Tier approach may be appropriate though.


A general guideline (that is testable)
- under it the specific testable guidelines where they are appropriate
- (sufficient techniques would not be in the guidelines but in support docs
from Access Board.


Gregg
-- ------------------------------
Gregg C Vanderheiden Ph.D.


> -----Original Message-----
> From: = EMAIL ADDRESS REMOVED = [mailto:teitac-telecom-
> = EMAIL ADDRESS REMOVED = ] On Behalf Of Jasionowski, Tony
> Sent: Monday, March 26, 2007 1:17 PM
> To: = EMAIL ADDRESS REMOVED =
> Subject: [teitac-telecom] teitac-telecom, PSTN Reference
>
> Paul,
> Noted, PSTN is also not acceptable for the reasons you passionately
> mention, therefore, I will investigate other suitable alternatives.
> Tony Jasionowski
> Panasonic
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Mon, 26 Mar 2007 09:28:09 -0600
> From: "Michaelis, Paul R. (Paul)" < = EMAIL ADDRESS REMOVED = >
> Subject: Re: [teitac-telecom] teitac-telecom, PSTN Reference
> To: "TEITAC Telecommunications Subcommittee"
> < = EMAIL ADDRESS REMOVED = >
> Message-ID:
>
> < = EMAIL ADDRESS REMOVED = >
>
> Content-Type: text/plain; charset="us-ascii"
>
> Tony,
>
> Quoting from the web page you cited:
>
> "Public Switched Telephone Network communications (PSTN, T.70) The
> collection of interconnected systems operated by the various telephone
> companies and administrations (telcos and PTTs) around the world. Also
> known as the Plain Old Telephone System (POTS) in contrast to xDSL and
> ISDN (not to mention other forms of PANS)."
>
> Note that this definition seems to say that services such as ISDN are
> *not* considered to be PSTN. Presumably, this would also mean that
> digital telephones, operating behind a PBX, are not PSTN. These phones
> are not IP either. This would mean that the proposal to classify
> equipment as either PSTN or IP will leave an entire category of telecom
> equipment without an obvious home.
>
> A reason why I am passionate about this issue is that I've wasted a
> tremendous amount of time over the past seven years, arguing with people
> -- including people in my own company -- about how to interpret the
> Section 508 requirements. "This requirement means this!" "No, it means
> that!!!" As part of the Section 508 refresh, we need to write
> unambiguous requirements that cannot be misinterpreted. Without that,
> contract officers will continue to buy whatever the heck they want,
> manufacturers will continue to sell inaccessible solutions to the
> government, and the likelihood that my company will let me build
> anything else will be close to nil.
>
> Getting back to the use of "PSTN" to describe non-IP phones, my fear is
> that some people who are looking for an excuse to avoid investing in
> accessibility -- including people in my own company -- will claim that
> ISDN and digital phones behind a PBX are exempt because they don't fall
> into either category. During the next seven years, I want to spend more
> time building solutions, and less time arguing about whether they ought
> to be built.
>
> -- Paul Michaelis
>
>
>
>
> -----Original Message-----
> From: Jasionowski, Tony [mailto: = EMAIL ADDRESS REMOVED = ]
> Sent: Monday, March 26, 2007 7:42 AM
> To: = EMAIL ADDRESS REMOVED =
> Subject: [teitac-telecom] teitac-telecom, PSTN Reference
>
> Paul,
> "wired analog and wired non-IP digital" seems odd considering we also
> have "cordless analog and digital". I suggest we stick with PSTN for now
> unless someone can propose acceptable alternative term. FYI, anyone can
> easily find the definition of PSTN at several web sites including:
> http://dictionary.reference.com/browse/pstn
> Therefore, PSTN may not be so confusing after all.
> Tony Jasionowski
> Panasonic
>
>
> Message: 1
> Date: Sat, 24 Mar 2007 17:41:44 -0600
> From: "Michaelis, Paul R. (Paul)" < = EMAIL ADDRESS REMOVED = >
> Subject: Re: [teitac-telecom] Telecommunications Working Group- Draft
> 1 Template for 508 in WORD
> To: "TEITAC Telecommunications Subcommittee"
> < = EMAIL ADDRESS REMOVED = >
> Cc: = EMAIL ADDRESS REMOVED = , Creagan Tim
> < = EMAIL ADDRESS REMOVED = >
> Message-ID:
>
> < = EMAIL ADDRESS REMOVED = >
>
> Content-Type: text/plain; charset="us-ascii"
>
> Regarding the reference to "PSTN" versus "IP" in many of the proposed
> requirements, I agree that IP telephones should be treated differently
> but am concerned that describing the non-IP systems as "PSTN" will
> create a lot of confusion.
>
>
>
> The "PSTN" is the Public Switched Telephone Network. If asked to
> describe a PSTN telephony endpoint, I imagine that most telecom
> specialists would say it was an analog device that complies with the FCC
> regulations that govern residential telephones. If we use this
> definition, I can't remember the last time I've seen a government
> procurement of telecom equipment that falls into this category.
>
>
>
> There are at least three different categories of non-IP wired telephones
> in common use today:
>
>
>
> Residential analog. (This is what most folks would classify as a "PSTN
> phone.")
>
>
>
> Enterprise analog. (The distinction between these phones and
> residential analog sets is that the enterprise sets connect to the PSTN
> via a PBX or switch that is owned by the enterprise. An important
> electrical distinction is that, unlike enterprise analog telephones,
> residential telephones are required to do "automatic loop length
> compensation" to account for distance-related differences in electrical
> resistance and capacitance in the line between the phone and the
> associated central office. Another important distinction is that many
> enterprise analog solutions are actually hybrid analog/digital sets.
> The audio stream is carried as traditional analog, supplemented by
> digital signaling that, for example, controls the phone's display.)
>
>
>
> Enterprise digital. (This is what is purchased in the vast majority of
> non-IP wired telephony procurements by the government. All audio
> transmissions entering or leaving the phone are digitally encoded,
> typically using the G.711 algorithm that I described in a previous
> message. Signaling and call control is also digital, typically using
> protocols that are proprietary to the individual manufacturers.)
>
>
>
> Wired residential analog systems, wired enterprise analog systems, and
> wired enterprise digital systems are able to transmit Baudot TTY signals
> with 100% reliability. IP telephony is different.
>
>
>
> Depending on network characteristics, the mechanisms that are used in
> order to transport voice signals within IP networks are not always
> suitable for transporting Baudot TTY tones. Common sources of
> impairment include packet loss and the use of voice-optimized audio
> compression algorithms, such as G.729. For this reason, a traditional
> TTY device used in conjunction with an IP phone (for example, via an
> acoustic coupler) is not always going to be reliable.
>
>
>
> The good news is that, although not yet in common use, there are
> international standards that describe how to transport text and Baudot
> tones reliably on IP networks. In general, these techniques do not use
> the same audio encoding and transmission mechanisms that are used for
> voice. I agree completely that the availability of these techniques,
> coupled with the inherent unreliability of Baudot TTY transmissions via
> the "voice channels" of IP telephone networks, makes it essential that
> we treat IP telephony as a special case in the Section 508 refresh.
>
>
>
> Getting back to the original topic of my message... We need a term
> other than PSTN to describe non-IP wired telephony. Ideally, it should
> be a term or description that would make sense to someone who is not
> knowledgeable about telephone engineering. To start the ball rolling, I
> suggest "wired analog and wired non-IP digital" as a substitute for
> PSTN. (I deliberately use the word "wired" because wireless devices
> have special characteristics that may need to be addressed separately.)
>
>
>
> -- Paul Michaelis
>
>
>
>
>
>
>

From: Gregg Vanderheiden
Date: Sat, Mar 31 2007 4:10 PM
Subject: Re: teitac-telecom, PSTN Reference

Hi Tom

Remember that there were three types of systems proposed.

The Public Analog, the Public IP and all other closed systems.

All of the government phones connect to the PSTN or emerging IP/SIP systems.
If they didn't you couldn't make a call.

Most of the government phones are part of a system though and only connect
to the PSTN through gateways or call managers. Making a call from one
phone to another inside an agency may not ever touch the PSTN. It would
simply be phone to phone. Some of those phones use different standards and
some use proprietary methods to communicate between phone and between the
phone and the call manager/server/gateway to the PSTN.

The problem then breaks down into three parts.


1) can the person with a disability use the terminal device (phone) and/or
can they connect any AT they need to it.

2) can the connection between the terminal device (phone) and the public
network (or between two phones not on the public network) carry the voice
and text and possibly video reliably and accurately.

3) when the call hits the public phone system, is it (the voice, text and
possibly video) in the right format to travel reliably on the network and to
work with the devices (standard phones or AT) at the other end.

What will work on the PSTN is different from what will work on the IP/SIP
network. And, if the two ends done use the same protocol or support at
least one common 'universal' format for voice/text/video then the call
cannot be completed. Hence the need for established standards for both the
PSTN and the IP/SIP networks.



Does this help?


Gregg
-- ------------------------------
Gregg C Vanderheiden Ph.D.



> -----Original Message-----
> From: = EMAIL ADDRESS REMOVED =
> [mailto: = EMAIL ADDRESS REMOVED = ] On Behalf Of Tom Brett
> Sent: Saturday, March 31, 2007 5:09 PM
> To: 'TEITAC Telecommunications Subcommittee'
> Subject: Re: [teitac-telecom] teitac-telecom, PSTN Reference
>
> How would a public phone system be defined?
>
> I am not sure it can be said that all government
> telecommunication systems fall into a PSTN or IP
> classification. If the government is using something other
> than a PSTN or IP system it would need to be considered public.
>
> Tom Brett
>
>
> -----Original Message-----
> From: = EMAIL ADDRESS REMOVED =
> [mailto: = EMAIL ADDRESS REMOVED = ] On Behalf Of
> Gregg Vanderheiden
> Sent: Saturday, March 31, 2007 3:52 PM
> To: 'TEITAC Telecommunications Subcommittee'
> Subject: Re: [teitac-telecom] teitac-telecom, PSTN Reference
>
> See previous post.
>
> We only need to talk about the public phone systems. (The
> PSTN and IP)
>
> For other systems - we should treat them as proprietary and
> keep our hands off until they meet with the public systems.
> At that time they would need to be in the common public format.
>
> There are too many non-public technologies and it would not
> be possible or appropriate to specify what form they should
> use internally.
>
>
>
> I think the Two Tier approach may be appropriate though.
>
>
> A general guideline (that is testable)
> - under it the specific testable guidelines where they are
> appropriate
> - (sufficient techniques would not be in the guidelines but
> in support docs from Access Board.
>
>
> Gregg
> -- ------------------------------
> Gregg C Vanderheiden Ph.D.
>
>
> > -----Original Message-----
> > From: = EMAIL ADDRESS REMOVED =
> [mailto:teitac-telecom-
> > = EMAIL ADDRESS REMOVED = ] On Behalf Of Jasionowski, Tony
> > Sent: Monday, March 26, 2007 1:17 PM
> > To: = EMAIL ADDRESS REMOVED =
> > Subject: [teitac-telecom] teitac-telecom, PSTN Reference
> >
> > Paul,
> > Noted, PSTN is also not acceptable for the reasons you passionately
> > mention, therefore, I will investigate other suitable alternatives.
> > Tony Jasionowski
> > Panasonic
> >
> ----------------------------------------------------------------------
> >
> > Message: 1
> > Date: Mon, 26 Mar 2007 09:28:09 -0600
> > From: "Michaelis, Paul R. (Paul)" < = EMAIL ADDRESS REMOVED = >
> > Subject: Re: [teitac-telecom] teitac-telecom, PSTN Reference
> > To: "TEITAC Telecommunications Subcommittee"
> > < = EMAIL ADDRESS REMOVED = >
> > Message-ID:
> >
> >
> < = EMAIL ADDRESS REMOVED =
> > m>
> >
> > Content-Type: text/plain; charset="us-ascii"
> >
> > Tony,
> >
> > Quoting from the web page you cited:
> >
> > "Public Switched Telephone Network communications (PSTN, T.70) The
> > collection of interconnected systems operated by the
> various telephone
> > companies and administrations (telcos and PTTs) around the
> world. Also
> > known as the Plain Old Telephone System (POTS) in contrast
> to xDSL and
> > ISDN (not to mention other forms of PANS)."
> >
> > Note that this definition seems to say that services such
> as ISDN are
> > *not* considered to be PSTN. Presumably, this would also mean that
> > digital telephones, operating behind a PBX, are not PSTN. These
> > phones are not IP either. This would mean that the proposal to
> > classify equipment as either PSTN or IP will leave an
> entire category
> > of telecom equipment without an obvious home.
> >
> > A reason why I am passionate about this issue is that I've wasted a
> > tremendous amount of time over the past seven years, arguing with
> > people
> > -- including people in my own company -- about how to interpret the
> > Section 508 requirements. "This requirement means this!" "No, it
> > means that!!!" As part of the Section 508 refresh, we need
> to write
> > unambiguous requirements that cannot be misinterpreted.
> Without that,
> > contract officers will continue to buy whatever the heck they want,
> > manufacturers will continue to sell inaccessible solutions to the
> > government, and the likelihood that my company will let me build
> > anything else will be close to nil.
> >
> > Getting back to the use of "PSTN" to describe non-IP
> phones, my fear
> > is that some people who are looking for an excuse to avoid
> investing
> > in accessibility -- including people in my own company --
> will claim
> > that ISDN and digital phones behind a PBX are exempt because they
> > don't fall into either category. During the next seven
> years, I want
> > to spend more time building solutions, and less time arguing about
> > whether they ought to be built.
> >
> > -- Paul Michaelis
> >
> >
> >
> >
> > -----Original Message-----
> > From: Jasionowski, Tony [mailto: = EMAIL ADDRESS REMOVED = ]
> > Sent: Monday, March 26, 2007 7:42 AM
> > To: = EMAIL ADDRESS REMOVED =
> > Subject: [teitac-telecom] teitac-telecom, PSTN Reference
> >
> > Paul,
> > "wired analog and wired non-IP digital" seems odd
> considering we also
> > have "cordless analog and digital". I suggest we stick with
> PSTN for
> > now unless someone can propose acceptable alternative term. FYI,
> > anyone can easily find the definition of PSTN at several
> web sites including:
> > http://dictionary.reference.com/browse/pstn
> > Therefore, PSTN may not be so confusing after all.
> > Tony Jasionowski
> > Panasonic
> >
> >
> > Message: 1
> > Date: Sat, 24 Mar 2007 17:41:44 -0600
> > From: "Michaelis, Paul R. (Paul)" < = EMAIL ADDRESS REMOVED = >
> > Subject: Re: [teitac-telecom] Telecommunications Working
> Group- Draft
> > 1 Template for 508 in WORD
> > To: "TEITAC Telecommunications Subcommittee"
> > < = EMAIL ADDRESS REMOVED = >
> > Cc: = EMAIL ADDRESS REMOVED = , Creagan Tim
> > < = EMAIL ADDRESS REMOVED = >
> > Message-ID:
> >
> >
> < = EMAIL ADDRESS REMOVED =
> > m>
> >
> > Content-Type: text/plain; charset="us-ascii"
> >
> > Regarding the reference to "PSTN" versus "IP" in many of
> the proposed
> > requirements, I agree that IP telephones should be treated
> differently
> > but am concerned that describing the non-IP systems as "PSTN" will
> > create a lot of confusion.
> >
> >
> >
> > The "PSTN" is the Public Switched Telephone Network. If asked to
> > describe a PSTN telephony endpoint, I imagine that most telecom
> > specialists would say it was an analog device that complies
> with the
> > FCC regulations that govern residential telephones. If we use this
> > definition, I can't remember the last time I've seen a government
> > procurement of telecom equipment that falls into this category.
> >
> >
> >
> > There are at least three different categories of non-IP wired
> > telephones in common use today:
> >
> >
> >
> > Residential analog. (This is what most folks would classify as a
> > "PSTN
> > phone.")
> >
> >
> >
> > Enterprise analog. (The distinction between these phones and
> > residential analog sets is that the enterprise sets connect to the
> > PSTN via a PBX or switch that is owned by the enterprise. An
> > important electrical distinction is that, unlike enterprise analog
> > telephones, residential telephones are required to do
> "automatic loop
> > length compensation" to account for distance-related differences in
> > electrical resistance and capacitance in the line between the phone
> > and the associated central office. Another important
> distinction is
> > that many enterprise analog solutions are actually hybrid
> analog/digital sets.
> > The audio stream is carried as traditional analog, supplemented by
> > digital signaling that, for example, controls the phone's display.)
> >
> >
> >
> > Enterprise digital. (This is what is purchased in the vast
> majority
> > of non-IP wired telephony procurements by the government.
> All audio
> > transmissions entering or leaving the phone are digitally encoded,
> > typically using the G.711 algorithm that I described in a previous
> > message. Signaling and call control is also digital,
> typically using
> > protocols that are proprietary to the individual manufacturers.)
> >
> >
> >
> > Wired residential analog systems, wired enterprise analog
> systems, and
> > wired enterprise digital systems are able to transmit Baudot TTY
> > signals with 100% reliability. IP telephony is different.
> >
> >
> >
> > Depending on network characteristics, the mechanisms that
> are used in
> > order to transport voice signals within IP networks are not always
> > suitable for transporting Baudot TTY tones. Common sources of
> > impairment include packet loss and the use of voice-optimized audio
> > compression algorithms, such as G.729. For this reason, a
> traditional
> > TTY device used in conjunction with an IP phone (for
> example, via an
> > acoustic coupler) is not always going to be reliable.
> >
> >
> >
> > The good news is that, although not yet in common use, there are
> > international standards that describe how to transport text
> and Baudot
> > tones reliably on IP networks. In general, these techniques do not
> > use the same audio encoding and transmission mechanisms
> that are used
> > for voice. I agree completely that the availability of these
> > techniques, coupled with the inherent unreliability of Baudot TTY
> > transmissions via the "voice channels" of IP telephone
> networks, makes
> > it essential that we treat IP telephony as a special case
> in the Section 508 refresh.
> >
> >
> >
> > Getting back to the original topic of my message... We need a term
> > other than PSTN to describe non-IP wired telephony. Ideally, it
> > should be a term or description that would make sense to
> someone who
> > is not knowledgeable about telephone engineering. To start
> the ball
> > rolling, I suggest "wired analog and wired non-IP digital" as a
> > substitute for PSTN. (I deliberately use the word "wired" because
> > wireless devices have special characteristics that may need to be
> > addressed separately.)
> >
> >
> >
> > -- Paul Michaelis
> >
> >
> >
> >
> >
> >
> >

From: Jim Tobias
Date: Sat, Mar 31 2007 6:20 PM
Subject: Re: teitac-telecom, PSTN Reference

I don't get your point. Anything the feds use for voice communication, be
it internal, external, private,
public, gateway, intercom, wireless, CB, ... anything -- it's all E&IT, and
thus covered. If a vendor
uses a proprietary system from top to bottom, but it meets the accessibility
requirements on its own
and interoperates (looking only at accessibility) with all other systems
that the procuring agency
finds necessary, it's compliant. Am I missing something? As much as we may
want the telecom industry
to adhere to some non-proprietary standard, I don't think we can use 508 to
make that happen.

***
Jim Tobias
Inclusive Technologies
+1.732.441.0831 v/tty
+1.908.907.2387 mobile
skype jimtobias


> -----Original Message-----
> From: Gregg Vanderheiden [mailto: = EMAIL ADDRESS REMOVED = ]
> Sent: Saturday, March 31, 2007 7:07 PM
> To: 'TEITAC Telecommunications Subcommittee'
> Subject: Re: [teitac-telecom] teitac-telecom, PSTN Reference
>
> Hi Tom
>
> Remember that there were three types of systems proposed.
>
> The Public Analog, the Public IP and all other closed systems.
>
> All of the government phones connect to the PSTN or emerging
> IP/SIP systems.
> If they didn't you couldn't make a call.
>
> Most of the government phones are part of a system though and
> only connect
> to the PSTN through gateways or call managers. Making a
> call from one
> phone to another inside an agency may not ever touch the
> PSTN. It would
> simply be phone to phone. Some of those phones use
> different standards and
> some use proprietary methods to communicate between phone and
> between the phone and the call manager/server/gateway to the PSTN.
>
> The problem then breaks down into three parts.
>
>
> 1) can the person with a disability use the terminal device
> (phone) and/or can they connect any AT they need to it.
>
> 2) can the connection between the terminal device (phone) and
> the public network (or between two phones not on the public
> network) carry the voice and text and possibly video reliably
> and accurately.
>
> 3) when the call hits the public phone system, is it (the
> voice, text and possibly video) in the right format to travel
> reliably on the network and to work with the devices
> (standard phones or AT) at the other end.
>
> What will work on the PSTN is different from what will work
> on the IP/SIP network. And, if the two ends done use the
> same protocol or support at least one common 'universal'
> format for voice/text/video then the call
> cannot be completed. Hence the need for established
> standards for both the
> PSTN and the IP/SIP networks.
>
>
>
> Does this help?
>
>
> Gregg
> -- ------------------------------
> Gregg C Vanderheiden Ph.D.
>
>
>
> > -----Original Message-----
> > From: = EMAIL ADDRESS REMOVED =
> > [mailto: = EMAIL ADDRESS REMOVED = ] On Behalf
> Of Tom Brett
> > Sent: Saturday, March 31, 2007 5:09 PM
> > To: 'TEITAC Telecommunications Subcommittee'
> > Subject: Re: [teitac-telecom] teitac-telecom, PSTN Reference
> >
> > How would a public phone system be defined?
> >
> > I am not sure it can be said that all government telecommunication
> > systems fall into a PSTN or IP classification. If the government is
> > using something other than a PSTN or IP system it would need to be
> > considered public.
> >
> > Tom Brett
> >
> >
> > -----Original Message-----
> > From: = EMAIL ADDRESS REMOVED =
> > [mailto: = EMAIL ADDRESS REMOVED = ] On Behalf Of Gregg
> > Vanderheiden
> > Sent: Saturday, March 31, 2007 3:52 PM
> > To: 'TEITAC Telecommunications Subcommittee'
> > Subject: Re: [teitac-telecom] teitac-telecom, PSTN Reference
> >
> > See previous post.
> >
> > We only need to talk about the public phone systems. (The
> > PSTN and IP)
> >
> > For other systems - we should treat them as proprietary and
> keep our
> > hands off until they meet with the public systems.
> > At that time they would need to be in the common public format.
> >
> > There are too many non-public technologies and it would not be
> > possible or appropriate to specify what form they should use
> > internally.
> >
> >
> >
> > I think the Two Tier approach may be appropriate though.
> >
> >
> > A general guideline (that is testable)
> > - under it the specific testable guidelines where they are
> > appropriate
> > - (sufficient techniques would not be in the guidelines but in
> > support docs from Access Board.
> >
> >
> > Gregg
> > -- ------------------------------
> > Gregg C Vanderheiden Ph.D.
> >
> >
> > > -----Original Message-----
> > > From: = EMAIL ADDRESS REMOVED =
> > [mailto:teitac-telecom-
> > > = EMAIL ADDRESS REMOVED = ] On Behalf Of Jasionowski, Tony
> > > Sent: Monday, March 26, 2007 1:17 PM
> > > To: = EMAIL ADDRESS REMOVED =
> > > Subject: [teitac-telecom] teitac-telecom, PSTN Reference
> > >
> > > Paul,
> > > Noted, PSTN is also not acceptable for the reasons you
> passionately
> > > mention, therefore, I will investigate other suitable
> alternatives.
> > > Tony Jasionowski
> > > Panasonic
> > >
> >
> ----------------------------------------------------------------------
> > >
> > > Message: 1
> > > Date: Mon, 26 Mar 2007 09:28:09 -0600
> > > From: "Michaelis, Paul R. (Paul)" < = EMAIL ADDRESS REMOVED = >
> > > Subject: Re: [teitac-telecom] teitac-telecom, PSTN Reference
> > > To: "TEITAC Telecommunications Subcommittee"
> > > < = EMAIL ADDRESS REMOVED = >
> > > Message-ID:
> > >
> > >
> >
> < = EMAIL ADDRESS REMOVED =
> > > m>
> > >
> > > Content-Type: text/plain; charset="us-ascii"
> > >
> > > Tony,
> > >
> > > Quoting from the web page you cited:
> > >
> > > "Public Switched Telephone Network communications (PSTN,
> T.70) The
> > > collection of interconnected systems operated by the
> > various telephone
> > > companies and administrations (telcos and PTTs) around the
> > world. Also
> > > known as the Plain Old Telephone System (POTS) in contrast
> > to xDSL and
> > > ISDN (not to mention other forms of PANS)."
> > >
> > > Note that this definition seems to say that services such
> > as ISDN are
> > > *not* considered to be PSTN. Presumably, this would also
> mean that
> > > digital telephones, operating behind a PBX, are not PSTN. These
> > > phones are not IP either. This would mean that the proposal to
> > > classify equipment as either PSTN or IP will leave an
> > entire category
> > > of telecom equipment without an obvious home.
> > >
> > > A reason why I am passionate about this issue is that
> I've wasted a
> > > tremendous amount of time over the past seven years, arguing with
> > > people
> > > -- including people in my own company -- about how to
> interpret the
> > > Section 508 requirements. "This requirement means this!"
> "No, it
> > > means that!!!" As part of the Section 508 refresh, we need
> > to write
> > > unambiguous requirements that cannot be misinterpreted.
> > Without that,
> > > contract officers will continue to buy whatever the heck
> they want,
> > > manufacturers will continue to sell inaccessible solutions to the
> > > government, and the likelihood that my company will let me build
> > > anything else will be close to nil.
> > >
> > > Getting back to the use of "PSTN" to describe non-IP
> > phones, my fear
> > > is that some people who are looking for an excuse to avoid
> > investing
> > > in accessibility -- including people in my own company --
> > will claim
> > > that ISDN and digital phones behind a PBX are exempt because they
> > > don't fall into either category. During the next seven
> > years, I want
> > > to spend more time building solutions, and less time
> arguing about
> > > whether they ought to be built.
> > >
> > > -- Paul Michaelis
> > >
> > >
> > >
> > >
> > > -----Original Message-----
> > > From: Jasionowski, Tony [mailto: = EMAIL ADDRESS REMOVED = ]
> > > Sent: Monday, March 26, 2007 7:42 AM
> > > To: = EMAIL ADDRESS REMOVED =
> > > Subject: [teitac-telecom] teitac-telecom, PSTN Reference
> > >
> > > Paul,
> > > "wired analog and wired non-IP digital" seems odd
> > considering we also
> > > have "cordless analog and digital". I suggest we stick with
> > PSTN for
> > > now unless someone can propose acceptable alternative term. FYI,
> > > anyone can easily find the definition of PSTN at several
> > web sites including:
> > > http://dictionary.reference.com/browse/pstn
> > > Therefore, PSTN may not be so confusing after all.
> > > Tony Jasionowski
> > > Panasonic
> > >
> > >
> > > Message: 1
> > > Date: Sat, 24 Mar 2007 17:41:44 -0600
> > > From: "Michaelis, Paul R. (Paul)" < = EMAIL ADDRESS REMOVED = >
> > > Subject: Re: [teitac-telecom] Telecommunications Working
> > Group- Draft
> > > 1 Template for 508 in WORD
> > > To: "TEITAC Telecommunications Subcommittee"
> > > < = EMAIL ADDRESS REMOVED = >
> > > Cc: = EMAIL ADDRESS REMOVED = , Creagan Tim
> > > < = EMAIL ADDRESS REMOVED = >
> > > Message-ID:
> > >
> > >
> >
> < = EMAIL ADDRESS REMOVED =
> > > m>
> > >
> > > Content-Type: text/plain; charset="us-ascii"
> > >
> > > Regarding the reference to "PSTN" versus "IP" in many of
> > the proposed
> > > requirements, I agree that IP telephones should be treated
> > differently
> > > but am concerned that describing the non-IP systems as
> "PSTN" will
> > > create a lot of confusion.
> > >
> > >
> > >
> > > The "PSTN" is the Public Switched Telephone Network. If asked to
> > > describe a PSTN telephony endpoint, I imagine that most telecom
> > > specialists would say it was an analog device that complies
> > with the
> > > FCC regulations that govern residential telephones. If
> we use this
> > > definition, I can't remember the last time I've seen a government
> > > procurement of telecom equipment that falls into this category.
> > >
> > >
> > >
> > > There are at least three different categories of non-IP wired
> > > telephones in common use today:
> > >
> > >
> > >
> > > Residential analog. (This is what most folks would classify as a
> > > "PSTN
> > > phone.")
> > >
> > >
> > >
> > > Enterprise analog. (The distinction between these phones and
> > > residential analog sets is that the enterprise sets
> connect to the
> > > PSTN via a PBX or switch that is owned by the enterprise. An
> > > important electrical distinction is that, unlike
> enterprise analog
> > > telephones, residential telephones are required to do
> > "automatic loop
> > > length compensation" to account for distance-related
> differences in
> > > electrical resistance and capacitance in the line between
> the phone
> > > and the associated central office. Another important
> > distinction is
> > > that many enterprise analog solutions are actually hybrid
> > analog/digital sets.
> > > The audio stream is carried as traditional analog,
> supplemented by
> > > digital signaling that, for example, controls the phone's
> display.)
> > >
> > >
> > >
> > > Enterprise digital. (This is what is purchased in the vast
> > majority
> > > of non-IP wired telephony procurements by the government.
> > All audio
> > > transmissions entering or leaving the phone are digitally
> encoded,
> > > typically using the G.711 algorithm that I described in a
> previous
> > > message. Signaling and call control is also digital,
> > typically using
> > > protocols that are proprietary to the individual manufacturers.)
> > >
> > >
> > >
> > > Wired residential analog systems, wired enterprise analog
> > systems, and
> > > wired enterprise digital systems are able to transmit Baudot TTY
> > > signals with 100% reliability. IP telephony is different.
> > >
> > >
> > >
> > > Depending on network characteristics, the mechanisms that
> > are used in
> > > order to transport voice signals within IP networks are
> not always
> > > suitable for transporting Baudot TTY tones. Common sources of
> > > impairment include packet loss and the use of
> voice-optimized audio
> > > compression algorithms, such as G.729. For this reason, a
> > traditional
> > > TTY device used in conjunction with an IP phone (for
> > example, via an
> > > acoustic coupler) is not always going to be reliable.
> > >
> > >
> > >
> > > The good news is that, although not yet in common use, there are
> > > international standards that describe how to transport text
> > and Baudot
> > > tones reliably on IP networks. In general, these
> techniques do not
> > > use the same audio encoding and transmission mechanisms
> > that are used
> > > for voice. I agree completely that the availability of these
> > > techniques, coupled with the inherent unreliability of Baudot TTY
> > > transmissions via the "voice channels" of IP telephone
> > networks, makes
> > > it essential that we treat IP telephony as a special case
> > in the Section 508 refresh.
> > >
> > >
> > >
> > > Getting back to the original topic of my message... We
> need a term
> > > other than PSTN to describe non-IP wired telephony. Ideally, it
> > > should be a term or description that would make sense to
> > someone who
> > > is not knowledgeable about telephone engineering. To start
> > the ball
> > > rolling, I suggest "wired analog and wired non-IP digital" as a
> > > substitute for PSTN. (I deliberately use the word
> "wired" because
> > > wireless devices have special characteristics that may need to be
> > > addressed separately.)
> > >
> > >
> > >
> > > -- Paul Michaelis
> > >
> > >
> > >
> > >
> > >
> > >
> > >

From: Tom Brett
Date: Sun, Apr 01 2007 6:45 AM
Subject: Re: teitac-telecom, PSTN Reference

Jim said:

"...but it meets the accessibility requirements on its own and interoperates
(looking only at accessibility) with all other systems that the procuring
agency finds necessary, it's compliant."

>From this I think it is meant that it would be alright to develop a script
or accessibility process that would permit AT to work with the telecom
system. The vendor would be permitted to add-on scripting to the
application that would make it accessible.

If there have been scripts developed, for example Jaws scripts, which would
allow a blind user to operate a GUI type telecom system even though the
bitmaps are not labeled, I don't see the application being considered
compliant. While the application would be accessible it would not meet the
standards.

Should there be another type of exception to the rule that say...if the
application can be made accessible without complying with the standards, the
application complies with the standards?

Tom Brett

-----Original Message-----
From: = EMAIL ADDRESS REMOVED =
[mailto: = EMAIL ADDRESS REMOVED = ] On Behalf Of Jim Tobias
Sent: Saturday, March 31, 2007 9:19 PM
To: 'TEITAC Telecommunications Subcommittee'
Subject: Re: [teitac-telecom] teitac-telecom, PSTN Reference

I don't get your point. Anything the feds use for voice communication, be
it internal, external, private,
public, gateway, intercom, wireless, CB, ... anything -- it's all E&IT, and
thus covered. If a vendor
uses a proprietary system from top to bottom, but it meets the accessibility
requirements on its own
and interoperates (looking only at accessibility) with all other systems
that the procuring agency
finds necessary, it's compliant. Am I missing something? As much as we may
want the telecom industry
to adhere to some non-proprietary standard, I don't think we can use 508 to
make that happen.

***
Jim Tobias
Inclusive Technologies
+1.732.441.0831 v/tty
+1.908.907.2387 mobile
skype jimtobias


> -----Original Message-----
> From: Gregg Vanderheiden [mailto: = EMAIL ADDRESS REMOVED = ]
> Sent: Saturday, March 31, 2007 7:07 PM
> To: 'TEITAC Telecommunications Subcommittee'
> Subject: Re: [teitac-telecom] teitac-telecom, PSTN Reference
>
> Hi Tom
>
> Remember that there were three types of systems proposed.
>
> The Public Analog, the Public IP and all other closed systems.
>
> All of the government phones connect to the PSTN or emerging
> IP/SIP systems.
> If they didn't you couldn't make a call.
>
> Most of the government phones are part of a system though and
> only connect
> to the PSTN through gateways or call managers. Making a
> call from one
> phone to another inside an agency may not ever touch the
> PSTN. It would
> simply be phone to phone. Some of those phones use
> different standards and
> some use proprietary methods to communicate between phone and
> between the phone and the call manager/server/gateway to the PSTN.
>
> The problem then breaks down into three parts.
>
>
> 1) can the person with a disability use the terminal device
> (phone) and/or can they connect any AT they need to it.
>
> 2) can the connection between the terminal device (phone) and
> the public network (or between two phones not on the public
> network) carry the voice and text and possibly video reliably
> and accurately.
>
> 3) when the call hits the public phone system, is it (the
> voice, text and possibly video) in the right format to travel
> reliably on the network and to work with the devices
> (standard phones or AT) at the other end.
>
> What will work on the PSTN is different from what will work
> on the IP/SIP network. And, if the two ends done use the
> same protocol or support at least one common 'universal'
> format for voice/text/video then the call
> cannot be completed. Hence the need for established
> standards for both the
> PSTN and the IP/SIP networks.
>
>
>
> Does this help?
>
>
> Gregg
> -- ------------------------------
> Gregg C Vanderheiden Ph.D.
>
>
>
> > -----Original Message-----
> > From: = EMAIL ADDRESS REMOVED =
> > [mailto: = EMAIL ADDRESS REMOVED = ] On Behalf
> Of Tom Brett
> > Sent: Saturday, March 31, 2007 5:09 PM
> > To: 'TEITAC Telecommunications Subcommittee'
> > Subject: Re: [teitac-telecom] teitac-telecom, PSTN Reference
> >
> > How would a public phone system be defined?
> >
> > I am not sure it can be said that all government telecommunication
> > systems fall into a PSTN or IP classification. If the government is
> > using something other than a PSTN or IP system it would need to be
> > considered public.
> >
> > Tom Brett
> >
> >
> > -----Original Message-----
> > From: = EMAIL ADDRESS REMOVED =
> > [mailto: = EMAIL ADDRESS REMOVED = ] On Behalf Of Gregg
> > Vanderheiden
> > Sent: Saturday, March 31, 2007 3:52 PM
> > To: 'TEITAC Telecommunications Subcommittee'
> > Subject: Re: [teitac-telecom] teitac-telecom, PSTN Reference
> >
> > See previous post.
> >
> > We only need to talk about the public phone systems. (The
> > PSTN and IP)
> >
> > For other systems - we should treat them as proprietary and
> keep our
> > hands off until they meet with the public systems.
> > At that time they would need to be in the common public format.
> >
> > There are too many non-public technologies and it would not be
> > possible or appropriate to specify what form they should use
> > internally.
> >
> >
> >
> > I think the Two Tier approach may be appropriate though.
> >
> >
> > A general guideline (that is testable)
> > - under it the specific testable guidelines where they are
> > appropriate
> > - (sufficient techniques would not be in the guidelines but in
> > support docs from Access Board.
> >
> >
> > Gregg
> > -- ------------------------------
> > Gregg C Vanderheiden Ph.D.
> >
> >
> > > -----Original Message-----
> > > From: = EMAIL ADDRESS REMOVED =
> > [mailto:teitac-telecom-
> > > = EMAIL ADDRESS REMOVED = ] On Behalf Of Jasionowski, Tony
> > > Sent: Monday, March 26, 2007 1:17 PM
> > > To: = EMAIL ADDRESS REMOVED =
> > > Subject: [teitac-telecom] teitac-telecom, PSTN Reference
> > >
> > > Paul,
> > > Noted, PSTN is also not acceptable for the reasons you
> passionately
> > > mention, therefore, I will investigate other suitable
> alternatives.
> > > Tony Jasionowski
> > > Panasonic
> > >
> >
> ----------------------------------------------------------------------
> > >
> > > Message: 1
> > > Date: Mon, 26 Mar 2007 09:28:09 -0600
> > > From: "Michaelis, Paul R. (Paul)" < = EMAIL ADDRESS REMOVED = >
> > > Subject: Re: [teitac-telecom] teitac-telecom, PSTN Reference
> > > To: "TEITAC Telecommunications Subcommittee"
> > > < = EMAIL ADDRESS REMOVED = >
> > > Message-ID:
> > >
> > >
> >
> < = EMAIL ADDRESS REMOVED =
> > > m>
> > >
> > > Content-Type: text/plain; charset="us-ascii"
> > >
> > > Tony,
> > >
> > > Quoting from the web page you cited:
> > >
> > > "Public Switched Telephone Network communications (PSTN,
> T.70) The
> > > collection of interconnected systems operated by the
> > various telephone
> > > companies and administrations (telcos and PTTs) around the
> > world. Also
> > > known as the Plain Old Telephone System (POTS) in contrast
> > to xDSL and
> > > ISDN (not to mention other forms of PANS)."
> > >
> > > Note that this definition seems to say that services such
> > as ISDN are
> > > *not* considered to be PSTN. Presumably, this would also
> mean that
> > > digital telephones, operating behind a PBX, are not PSTN. These
> > > phones are not IP either. This would mean that the proposal to
> > > classify equipment as either PSTN or IP will leave an
> > entire category
> > > of telecom equipment without an obvious home.
> > >
> > > A reason why I am passionate about this issue is that
> I've wasted a
> > > tremendous amount of time over the past seven years, arguing with
> > > people
> > > -- including people in my own company -- about how to
> interpret the
> > > Section 508 requirements. "This requirement means this!"
> "No, it
> > > means that!!!" As part of the Section 508 refresh, we need
> > to write
> > > unambiguous requirements that cannot be misinterpreted.
> > Without that,
> > > contract officers will continue to buy whatever the heck
> they want,
> > > manufacturers will continue to sell inaccessible solutions to the
> > > government, and the likelihood that my company will let me build
> > > anything else will be close to nil.
> > >
> > > Getting back to the use of "PSTN" to describe non-IP
> > phones, my fear
> > > is that some people who are looking for an excuse to avoid
> > investing
> > > in accessibility -- including people in my own company --
> > will claim
> > > that ISDN and digital phones behind a PBX are exempt because they
> > > don't fall into either category. During the next seven
> > years, I want
> > > to spend more time building solutions, and less time
> arguing about
> > > whether they ought to be built.
> > >
> > > -- Paul Michaelis
> > >
> > >
> > >
> > >
> > > -----Original Message-----
> > > From: Jasionowski, Tony [mailto: = EMAIL ADDRESS REMOVED = ]
> > > Sent: Monday, March 26, 2007 7:42 AM
> > > To: = EMAIL ADDRESS REMOVED =
> > > Subject: [teitac-telecom] teitac-telecom, PSTN Reference
> > >
> > > Paul,
> > > "wired analog and wired non-IP digital" seems odd
> > considering we also
> > > have "cordless analog and digital". I suggest we stick with
> > PSTN for
> > > now unless someone can propose acceptable alternative term. FYI,
> > > anyone can easily find the definition of PSTN at several
> > web sites including:
> > > http://dictionary.reference.com/browse/pstn
> > > Therefore, PSTN may not be so confusing after all.
> > > Tony Jasionowski
> > > Panasonic
> > >
> > >
> > > Message: 1
> > > Date: Sat, 24 Mar 2007 17:41:44 -0600
> > > From: "Michaelis, Paul R. (Paul)" < = EMAIL ADDRESS REMOVED = >
> > > Subject: Re: [teitac-telecom] Telecommunications Working
> > Group- Draft
> > > 1 Template for 508 in WORD
> > > To: "TEITAC Telecommunications Subcommittee"
> > > < = EMAIL ADDRESS REMOVED = >
> > > Cc: = EMAIL ADDRESS REMOVED = , Creagan Tim
> > > < = EMAIL ADDRESS REMOVED = >
> > > Message-ID:
> > >
> > >
> >
> < = EMAIL ADDRESS REMOVED =
> > > m>
> > >
> > > Content-Type: text/plain; charset="us-ascii"
> > >
> > > Regarding the reference to "PSTN" versus "IP" in many of
> > the proposed
> > > requirements, I agree that IP telephones should be treated
> > differently
> > > but am concerned that describing the non-IP systems as
> "PSTN" will
> > > create a lot of confusion.
> > >
> > >
> > >
> > > The "PSTN" is the Public Switched Telephone Network. If asked to
> > > describe a PSTN telephony endpoint, I imagine that most telecom
> > > specialists would say it was an analog device that complies
> > with the
> > > FCC regulations that govern residential telephones. If
> we use this
> > > definition, I can't remember the last time I've seen a government
> > > procurement of telecom equipment that falls into this category.
> > >
> > >
> > >
> > > There are at least three different categories of non-IP wired
> > > telephones in common use today:
> > >
> > >
> > >
> > > Residential analog. (This is what most folks would classify as a
> > > "PSTN
> > > phone.")
> > >
> > >
> > >
> > > Enterprise analog. (The distinction between these phones and
> > > residential analog sets is that the enterprise sets
> connect to the
> > > PSTN via a PBX or switch that is owned by the enterprise. An
> > > important electrical distinction is that, unlike
> enterprise analog
> > > telephones, residential telephones are required to do
> > "automatic loop
> > > length compensation" to account for distance-related
> differences in
> > > electrical resistance and capacitance in the line between
> the phone
> > > and the associated central office. Another important
> > distinction is
> > > that many enterprise analog solutions are actually hybrid
> > analog/digital sets.
> > > The audio stream is carried as traditional analog,
> supplemented by
> > > digital signaling that, for example, controls the phone's
> display.)
> > >
> > >
> > >
> > > Enterprise digital. (This is what is purchased in the vast
> > majority
> > > of non-IP wired telephony procurements by the government.
> > All audio
> > > transmissions entering or leaving the phone are digitally
> encoded,
> > > typically using the G.711 algorithm that I described in a
> previous
> > > message. Signaling and call control is also digital,
> > typically using
> > > protocols that are proprietary to the individual manufacturers.)
> > >
> > >
> > >
> > > Wired residential analog systems, wired enterprise analog
> > systems, and
> > > wired enterprise digital systems are able to transmit Baudot TTY
> > > signals with 100% reliability. IP telephony is different.
> > >
> > >
> > >
> > > Depending on network characteristics, the mechanisms that
> > are used in
> > > order to transport voice signals within IP networks are
> not always
> > > suitable for transporting Baudot TTY tones. Common sources of
> > > impairment include packet loss and the use of
> voice-optimized audio
> > > compression algorithms, such as G.729. For this reason, a
> > traditional
> > > TTY device used in conjunction with an IP phone (for
> > example, via an
> > > acoustic coupler) is not always going to be reliable.
> > >
> > >
> > >
> > > The good news is that, although not yet in common use, there are
> > > international standards that describe how to transport text
> > and Baudot
> > > tones reliably on IP networks. In general, these
> techniques do not
> > > use the same audio encoding and transmission mechanisms
> > that are used
> > > for voice. I agree completely that the availability of these
> > > techniques, coupled with the inherent unreliability of Baudot TTY
> > > transmissions via the "voice channels" of IP telephone
> > networks, makes
> > > it essential that we treat IP telephony as a special case
> > in the Section 508 refresh.
> > >
> > >
> > >
> > > Getting back to the original topic of my message... We
> need a term
> > > other than PSTN to describe non-IP wired telephony. Ideally, it
> > > should be a term or description that would make sense to
> > someone who
> > > is not knowledgeable about telephone engineering. To start
> > the ball
> > > rolling, I suggest "wired analog and wired non-IP digital" as a
> > > substitute for PSTN. (I deliberately use the word
> "wired" because
> > > wireless devices have special characteristics that may need to be
> > > addressed separately.)
> > >
> > >
> > >
> > > -- Paul Michaelis
> > >
> > >
> > >
> > >
> > >
> > >
> > >

From: David Poehlman
Date: Sun, Apr 01 2007 7:25 AM
Subject: Re: teitac-telecom, PSTN Reference

On Apr 1, 2007, at 8:40 AM, Tom Brett wrote:

....Should there be another type of exception to the rule that
say...if the
application can be made accessible without complying with the
standards, the
application complies with the standards?
I would hope not tom. First, jaws is not the be and end all of
accessability and second, what if jaws changes and on and on and on???

-----Original Message-----
From: = EMAIL ADDRESS REMOVED =
[mailto: = EMAIL ADDRESS REMOVED = ] On Behalf Of Jim Tobias
Sent: Saturday, March 31, 2007 9:19 PM
To: 'TEITAC Telecommunications Subcommittee'
Subject: Re: [teitac-telecom] teitac-telecom, PSTN Reference

I don't get your point. Anything the feds use for voice
communication, be
it internal, external, private,
public, gateway, intercom, wireless, CB, ... anything -- it's all
E&IT, and
thus covered. If a vendor
uses a proprietary system from top to bottom, but it meets the
accessibility
requirements on its own
and interoperates (looking only at accessibility) with all other systems
that the procuring agency
finds necessary, it's compliant. Am I missing something? As much as
we may
want the telecom industry
to adhere to some non-proprietary standard, I don't think we can use
508 to
make that happen.

***
Jim Tobias
Inclusive Technologies
+1.732.441.0831 v/tty
+1.908.907.2387 mobile
skype jimtobias


> -----Original Message-----
> From: Gregg Vanderheiden [mailto: = EMAIL ADDRESS REMOVED = ]
> Sent: Saturday, March 31, 2007 7:07 PM
> To: 'TEITAC Telecommunications Subcommittee'
> Subject: Re: [teitac-telecom] teitac-telecom, PSTN Reference
>
> Hi Tom
>
> Remember that there were three types of systems proposed.
>
> The Public Analog, the Public IP and all other closed systems.
>
> All of the government phones connect to the PSTN or emerging
> IP/SIP systems.
> If they didn't you couldn't make a call.
>
> Most of the government phones are part of a system though and
> only connect
> to the PSTN through gateways or call managers. Making a
> call from one
> phone to another inside an agency may not ever touch the
> PSTN. It would
> simply be phone to phone. Some of those phones use
> different standards and
> some use proprietary methods to communicate between phone and
> between the phone and the call manager/server/gateway to the PSTN.
>
> The problem then breaks down into three parts.
>
>
> 1) can the person with a disability use the terminal device
> (phone) and/or can they connect any AT they need to it.
>
> 2) can the connection between the terminal device (phone) and
> the public network (or between two phones not on the public
> network) carry the voice and text and possibly video reliably
> and accurately.
>
> 3) when the call hits the public phone system, is it (the
> voice, text and possibly video) in the right format to travel
> reliably on the network and to work with the devices
> (standard phones or AT) at the other end.
>
> What will work on the PSTN is different from what will work
> on the IP/SIP network. And, if the two ends done use the
> same protocol or support at least one common 'universal'
> format for voice/text/video then the call
> cannot be completed. Hence the need for established
> standards for both the
> PSTN and the IP/SIP networks.
>
>
>
> Does this help?
>
>
> Gregg
> -- ------------------------------
> Gregg C Vanderheiden Ph.D.
>
>
>
>> -----Original Message-----
>> From: = EMAIL ADDRESS REMOVED =
>> [mailto: = EMAIL ADDRESS REMOVED = ] On Behalf
> Of Tom Brett
>> Sent: Saturday, March 31, 2007 5:09 PM
>> To: 'TEITAC Telecommunications Subcommittee'
>> Subject: Re: [teitac-telecom] teitac-telecom, PSTN Reference
>>
>> How would a public phone system be defined?
>>
>> I am not sure it can be said that all government telecommunication
>> systems fall into a PSTN or IP classification. If the government is
>> using something other than a PSTN or IP system it would need to be
>> considered public.
>>
>> Tom Brett
>>
>>
>> -----Original Message-----
>> From: = EMAIL ADDRESS REMOVED =
>> [mailto: = EMAIL ADDRESS REMOVED = ] On Behalf Of Gregg
>> Vanderheiden
>> Sent: Saturday, March 31, 2007 3:52 PM
>> To: 'TEITAC Telecommunications Subcommittee'
>> Subject: Re: [teitac-telecom] teitac-telecom, PSTN Reference
>>
>> See previous post.
>>
>> We only need to talk about the public phone systems. (The
>> PSTN and IP)
>>
>> For other systems - we should treat them as proprietary and
> keep our
>> hands off until they meet with the public systems.
>> At that time they would need to be in the common public format.
>>
>> There are too many non-public technologies and it would not be
>> possible or appropriate to specify what form they should use
>> internally.
>>
>>
>>
>> I think the Two Tier approach may be appropriate though.
>>
>>
>> A general guideline (that is testable)
>> - under it the specific testable guidelines where they are
>> appropriate
>> - (sufficient techniques would not be in the guidelines but in
>> support docs from Access Board.
>>
>>
>> Gregg
>> -- ------------------------------
>> Gregg C Vanderheiden Ph.D.
>>
>>
>>> -----Original Message-----
>>> From: = EMAIL ADDRESS REMOVED =
>> [mailto:teitac-telecom-
>>> = EMAIL ADDRESS REMOVED = ] On Behalf Of Jasionowski, Tony
>>> Sent: Monday, March 26, 2007 1:17 PM
>>> To: = EMAIL ADDRESS REMOVED =
>>> Subject: [teitac-telecom] teitac-telecom, PSTN Reference
>>>
>>> Paul,
>>> Noted, PSTN is also not acceptable for the reasons you
> passionately
>>> mention, therefore, I will investigate other suitable
> alternatives.
>>> Tony Jasionowski
>>> Panasonic
>>>
>>
> ----------------------------------------------------------------------
>>>
>>> Message: 1
>>> Date: Mon, 26 Mar 2007 09:28:09 -0600
>>> From: "Michaelis, Paul R. (Paul)" < = EMAIL ADDRESS REMOVED = >
>>> Subject: Re: [teitac-telecom] teitac-telecom, PSTN Reference
>>> To: "TEITAC Telecommunications Subcommittee"
>>> < = EMAIL ADDRESS REMOVED = >
>>> Message-ID:
>>>
>>>
>>
> < = EMAIL ADDRESS REMOVED =
>>> m>
>>>
>>> Content-Type: text/plain; charset="us-ascii"
>>>
>>> Tony,
>>>
>>> Quoting from the web page you cited:
>>>
>>> "Public Switched Telephone Network communications (PSTN,
> T.70) The
>>> collection of interconnected systems operated by the
>> various telephone
>>> companies and administrations (telcos and PTTs) around the
>> world. Also
>>> known as the Plain Old Telephone System (POTS) in contrast
>> to xDSL and
>>> ISDN (not to mention other forms of PANS)."
>>>
>>> Note that this definition seems to say that services such
>> as ISDN are
>>> *not* considered to be PSTN. Presumably, this would also
> mean that
>>> digital telephones, operating behind a PBX, are not PSTN. These
>>> phones are not IP either. This would mean that the proposal to
>>> classify equipment as either PSTN or IP will leave an
>> entire category
>>> of telecom equipment without an obvious home.
>>>
>>> A reason why I am passionate about this issue is that
> I've wasted a
>>> tremendous amount of time over the past seven years, arguing with
>>> people
>>> -- including people in my own company -- about how to
> interpret the
>>> Section 508 requirements. "This requirement means this!"
> "No, it
>>> means that!!!" As part of the Section 508 refresh, we need
>> to write
>>> unambiguous requirements that cannot be misinterpreted.
>> Without that,
>>> contract officers will continue to buy whatever the heck
> they want,
>>> manufacturers will continue to sell inaccessible solutions to the
>>> government, and the likelihood that my company will let me build
>>> anything else will be close to nil.
>>>
>>> Getting back to the use of "PSTN" to describe non-IP
>> phones, my fear
>>> is that some people who are looking for an excuse to avoid
>> investing
>>> in accessibility -- including people in my own company --
>> will claim
>>> that ISDN and digital phones behind a PBX are exempt because they
>>> don't fall into either category. During the next seven
>> years, I want
>>> to spend more time building solutions, and less time
> arguing about
>>> whether they ought to be built.
>>>
>>> -- Paul Michaelis
>>>
>>>
>>>
>>>
>>> -----Original Message-----
>>> From: Jasionowski, Tony [mailto: = EMAIL ADDRESS REMOVED = ]
>>> Sent: Monday, March 26, 2007 7:42 AM
>>> To: = EMAIL ADDRESS REMOVED =
>>> Subject: [teitac-telecom] teitac-telecom, PSTN Reference
>>>
>>> Paul,
>>> "wired analog and wired non-IP digital" seems odd
>> considering we also
>>> have "cordless analog and digital". I suggest we stick with
>> PSTN for
>>> now unless someone can propose acceptable alternative term. FYI,
>>> anyone can easily find the definition of PSTN at several
>> web sites including:
>>> http://dictionary.reference.com/browse/pstn
>>> Therefore, PSTN may not be so confusing after all.
>>> Tony Jasionowski
>>> Panasonic
>>>
>>>
>>> Message: 1
>>> Date: Sat, 24 Mar 2007 17:41:44 -0600
>>> From: "Michaelis, Paul R. (Paul)" < = EMAIL ADDRESS REMOVED = >
>>> Subject: Re: [teitac-telecom] Telecommunications Working
>> Group- Draft
>>> 1 Template for 508 in WORD
>>> To: "TEITAC Telecommunications Subcommittee"
>>> < = EMAIL ADDRESS REMOVED = >
>>> Cc: = EMAIL ADDRESS REMOVED = , Creagan Tim
>>> < = EMAIL ADDRESS REMOVED = >
>>> Message-ID:
>>>
>>>
>>
> < = EMAIL ADDRESS REMOVED =
>>> m>
>>>
>>> Content-Type: text/plain; charset="us-ascii"
>>>
>>> Regarding the reference to "PSTN" versus "IP" in many of
>> the proposed
>>> requirements, I agree that IP telephones should be treated
>> differently
>>> but am concerned that describing the non-IP systems as
> "PSTN" will
>>> create a lot of confusion.
>>>
>>>
>>>
>>> The "PSTN" is the Public Switched Telephone Network. If asked to
>>> describe a PSTN telephony endpoint, I imagine that most telecom
>>> specialists would say it was an analog device that complies
>> with the
>>> FCC regulations that govern residential telephones. If
> we use this
>>> definition, I can't remember the last time I've seen a government
>>> procurement of telecom equipment that falls into this category.
>>>
>>>
>>>
>>> There are at least three different categories of non-IP wired
>>> telephones in common use today:
>>>
>>>
>>>
>>> Residential analog. (This is what most folks would classify as a
>>> "PSTN
>>> phone.")
>>>
>>>
>>>
>>> Enterprise analog. (The distinction between these phones and
>>> residential analog sets is that the enterprise sets
> connect to the
>>> PSTN via a PBX or switch that is owned by the enterprise. An
>>> important electrical distinction is that, unlike
> enterprise analog
>>> telephones, residential telephones are required to do
>> "automatic loop
>>> length compensation" to account for distance-related
> differences in
>>> electrical resistance and capacitance in the line between
> the phone
>>> and the associated central office. Another important
>> distinction is
>>> that many enterprise analog solutions are actually hybrid
>> analog/digital sets.
>>> The audio stream is carried as traditional analog,
> supplemented by
>>> digital signaling that, for example, controls the phone's
> display.)
>>>
>>>
>>>
>>> Enterprise digital. (This is what is purchased in the vast
>> majority
>>> of non-IP wired telephony procurements by the government.
>> All audio
>>> transmissions entering or leaving the phone are digitally
> encoded,
>>> typically using the G.711 algorithm that I described in a
> previous
>>> message. Signaling and call control is also digital,
>> typically using
>>> protocols that are proprietary to the individual manufacturers.)
>>>
>>>
>>>
>>> Wired residential analog systems, wired enterprise analog
>> systems, and
>>> wired enterprise digital systems are able to transmit Baudot TTY
>>> signals with 100% reliability. IP telephony is different.
>>>
>>>
>>>
>>> Depending on network characteristics, the mechanisms that
>> are used in
>>> order to transport voice signals within IP networks are
> not always
>>> suitable for transporting Baudot TTY tones. Common sources of
>>> impairment include packet loss and the use of
> voice-optimized audio
>>> compression algorithms, such as G.729. For this reason, a
>> traditional
>>> TTY device used in conjunction with an IP phone (for
>> example, via an
>>> acoustic coupler) is not always going to be reliable.
>>>
>>>
>>>
>>> The good news is that, although not yet in common use, there are
>>> international standards that describe how to transport text
>> and Baudot
>>> tones reliably on IP networks. In general, these
> techniques do not
>>> use the same audio encoding and transmission mechanisms
>> that are used
>>> for voice. I agree completely that the availability of these
>>> techniques, coupled with the inherent unreliability of Baudot TTY
>>> transmissions via the "voice channels" of IP telephone
>> networks, makes
>>> it essential that we treat IP telephony as a special case
>> in the Section 508 refresh.
>>>
>>>
>>>
>>> Getting back to the original topic of my message... We
> need a term
>>> other than PSTN to describe non-IP wired telephony. Ideally, it
>>> should be a term or description that would make sense to
>> someone who
>>> is not knowledgeable about telephone engineering. To start
>> the ball
>>> rolling, I suggest "wired analog and wired non-IP digital" as a
>>> substitute for PSTN. (I deliberately use the word
> "wired" because
>>> wireless devices have special characteristics that may need to be
>>> addressed separately.)
>>>
>>>
>>>
>>> -- Paul Michaelis
>>>
>>>
>>>
>>>
>>>
>>>
>>>

From: Tom Brett
Date: Sun, Apr 01 2007 11:50 AM
Subject: Re: teitac-telecom, PSTN Reference

I agree but then we need to evaluate items according to the standards and
not to just being accessible.

Tom Brett


-----Original Message-----
From: = EMAIL ADDRESS REMOVED =
[mailto: = EMAIL ADDRESS REMOVED = ] On Behalf Of David Poehlman
Sent: Sunday, April 01, 2007 9:23 AM
To: TEITAC Telecommunications Subcommittee
Subject: Re: [teitac-telecom] teitac-telecom, PSTN Reference


On Apr 1, 2007, at 8:40 AM, Tom Brett wrote:

....Should there be another type of exception to the rule that
say...if the
application can be made accessible without complying with the
standards, the
application complies with the standards?
I would hope not tom. First, jaws is not the be and end all of
accessability and second, what if jaws changes and on and on and on???

-----Original Message-----
From: = EMAIL ADDRESS REMOVED =
[mailto: = EMAIL ADDRESS REMOVED = ] On Behalf Of Jim Tobias
Sent: Saturday, March 31, 2007 9:19 PM
To: 'TEITAC Telecommunications Subcommittee'
Subject: Re: [teitac-telecom] teitac-telecom, PSTN Reference

I don't get your point. Anything the feds use for voice
communication, be
it internal, external, private,
public, gateway, intercom, wireless, CB, ... anything -- it's all
E&IT, and
thus covered. If a vendor
uses a proprietary system from top to bottom, but it meets the
accessibility
requirements on its own
and interoperates (looking only at accessibility) with all other systems
that the procuring agency
finds necessary, it's compliant. Am I missing something? As much as
we may
want the telecom industry
to adhere to some non-proprietary standard, I don't think we can use
508 to
make that happen.

***
Jim Tobias
Inclusive Technologies
+1.732.441.0831 v/tty
+1.908.907.2387 mobile
skype jimtobias


> -----Original Message-----
> From: Gregg Vanderheiden [mailto: = EMAIL ADDRESS REMOVED = ]
> Sent: Saturday, March 31, 2007 7:07 PM
> To: 'TEITAC Telecommunications Subcommittee'
> Subject: Re: [teitac-telecom] teitac-telecom, PSTN Reference
>
> Hi Tom
>
> Remember that there were three types of systems proposed.
>
> The Public Analog, the Public IP and all other closed systems.
>
> All of the government phones connect to the PSTN or emerging
> IP/SIP systems.
> If they didn't you couldn't make a call.
>
> Most of the government phones are part of a system though and
> only connect
> to the PSTN through gateways or call managers. Making a
> call from one
> phone to another inside an agency may not ever touch the
> PSTN. It would
> simply be phone to phone. Some of those phones use
> different standards and
> some use proprietary methods to communicate between phone and
> between the phone and the call manager/server/gateway to the PSTN.
>
> The problem then breaks down into three parts.
>
>
> 1) can the person with a disability use the terminal device
> (phone) and/or can they connect any AT they need to it.
>
> 2) can the connection between the terminal device (phone) and
> the public network (or between two phones not on the public
> network) carry the voice and text and possibly video reliably
> and accurately.
>
> 3) when the call hits the public phone system, is it (the
> voice, text and possibly video) in the right format to travel
> reliably on the network and to work with the devices
> (standard phones or AT) at the other end.
>
> What will work on the PSTN is different from what will work
> on the IP/SIP network. And, if the two ends done use the
> same protocol or support at least one common 'universal'
> format for voice/text/video then the call
> cannot be completed. Hence the need for established
> standards for both the
> PSTN and the IP/SIP networks.
>
>
>
> Does this help?
>
>
> Gregg
> -- ------------------------------
> Gregg C Vanderheiden Ph.D.
>
>
>
>> -----Original Message-----
>> From: = EMAIL ADDRESS REMOVED =
>> [mailto: = EMAIL ADDRESS REMOVED = ] On Behalf
> Of Tom Brett
>> Sent: Saturday, March 31, 2007 5:09 PM
>> To: 'TEITAC Telecommunications Subcommittee'
>> Subject: Re: [teitac-telecom] teitac-telecom, PSTN Reference
>>
>> How would a public phone system be defined?
>>
>> I am not sure it can be said that all government telecommunication
>> systems fall into a PSTN or IP classification. If the government is
>> using something other than a PSTN or IP system it would need to be
>> considered public.
>>
>> Tom Brett
>>
>>
>> -----Original Message-----
>> From: = EMAIL ADDRESS REMOVED =
>> [mailto: = EMAIL ADDRESS REMOVED = ] On Behalf Of Gregg
>> Vanderheiden
>> Sent: Saturday, March 31, 2007 3:52 PM
>> To: 'TEITAC Telecommunications Subcommittee'
>> Subject: Re: [teitac-telecom] teitac-telecom, PSTN Reference
>>
>> See previous post.
>>
>> We only need to talk about the public phone systems. (The
>> PSTN and IP)
>>
>> For other systems - we should treat them as proprietary and
> keep our
>> hands off until they meet with the public systems.
>> At that time they would need to be in the common public format.
>>
>> There are too many non-public technologies and it would not be
>> possible or appropriate to specify what form they should use
>> internally.
>>
>>
>>
>> I think the Two Tier approach may be appropriate though.
>>
>>
>> A general guideline (that is testable)
>> - under it the specific testable guidelines where they are
>> appropriate
>> - (sufficient techniques would not be in the guidelines but in
>> support docs from Access Board.
>>
>>
>> Gregg
>> -- ------------------------------
>> Gregg C Vanderheiden Ph.D.
>>
>>
>>> -----Original Message-----
>>> From: = EMAIL ADDRESS REMOVED =
>> [mailto:teitac-telecom-
>>> = EMAIL ADDRESS REMOVED = ] On Behalf Of Jasionowski, Tony
>>> Sent: Monday, March 26, 2007 1:17 PM
>>> To: = EMAIL ADDRESS REMOVED =
>>> Subject: [teitac-telecom] teitac-telecom, PSTN Reference
>>>
>>> Paul,
>>> Noted, PSTN is also not acceptable for the reasons you
> passionately
>>> mention, therefore, I will investigate other suitable
> alternatives.
>>> Tony Jasionowski
>>> Panasonic
>>>
>>
> ----------------------------------------------------------------------
>>>
>>> Message: 1
>>> Date: Mon, 26 Mar 2007 09:28:09 -0600
>>> From: "Michaelis, Paul R. (Paul)" < = EMAIL ADDRESS REMOVED = >
>>> Subject: Re: [teitac-telecom] teitac-telecom, PSTN Reference
>>> To: "TEITAC Telecommunications Subcommittee"
>>> < = EMAIL ADDRESS REMOVED = >
>>> Message-ID:
>>>
>>>
>>
> < = EMAIL ADDRESS REMOVED =
>>> m>
>>>
>>> Content-Type: text/plain; charset="us-ascii"
>>>
>>> Tony,
>>>
>>> Quoting from the web page you cited:
>>>
>>> "Public Switched Telephone Network communications (PSTN,
> T.70) The
>>> collection of interconnected systems operated by the
>> various telephone
>>> companies and administrations (telcos and PTTs) around the
>> world. Also
>>> known as the Plain Old Telephone System (POTS) in contrast
>> to xDSL and
>>> ISDN (not to mention other forms of PANS)."
>>>
>>> Note that this definition seems to say that services such
>> as ISDN are
>>> *not* considered to be PSTN. Presumably, this would also
> mean that
>>> digital telephones, operating behind a PBX, are not PSTN. These
>>> phones are not IP either. This would mean that the proposal to
>>> classify equipment as either PSTN or IP will leave an
>> entire category
>>> of telecom equipment without an obvious home.
>>>
>>> A reason why I am passionate about this issue is that
> I've wasted a
>>> tremendous amount of time over the past seven years, arguing with
>>> people
>>> -- including people in my own company -- about how to
> interpret the
>>> Section 508 requirements. "This requirement means this!"
> "No, it
>>> means that!!!" As part of the Section 508 refresh, we need
>> to write
>>> unambiguous requirements that cannot be misinterpreted.
>> Without that,
>>> contract officers will continue to buy whatever the heck
> they want,
>>> manufacturers will continue to sell inaccessible solutions to the
>>> government, and the likelihood that my company will let me build
>>> anything else will be close to nil.
>>>
>>> Getting back to the use of "PSTN" to describe non-IP
>> phones, my fear
>>> is that some people who are looking for an excuse to avoid
>> investing
>>> in accessibility -- including people in my own company --
>> will claim
>>> that ISDN and digital phones behind a PBX are exempt because they
>>> don't fall into either category. During the next seven
>> years, I want
>>> to spend more time building solutions, and less time
> arguing about
>>> whether they ought to be built.
>>>
>>> -- Paul Michaelis
>>>
>>>
>>>
>>>
>>> -----Original Message-----
>>> From: Jasionowski, Tony [mailto: = EMAIL ADDRESS REMOVED = ]
>>> Sent: Monday, March 26, 2007 7:42 AM
>>> To: = EMAIL ADDRESS REMOVED =
>>> Subject: [teitac-telecom] teitac-telecom, PSTN Reference
>>>
>>> Paul,
>>> "wired analog and wired non-IP digital" seems odd
>> considering we also
>>> have "cordless analog and digital". I suggest we stick with
>> PSTN for
>>> now unless someone can propose acceptable alternative term. FYI,
>>> anyone can easily find the definition of PSTN at several
>> web sites including:
>>> http://dictionary.reference.com/browse/pstn
>>> Therefore, PSTN may not be so confusing after all.
>>> Tony Jasionowski
>>> Panasonic
>>>
>>>
>>> Message: 1
>>> Date: Sat, 24 Mar 2007 17:41:44 -0600
>>> From: "Michaelis, Paul R. (Paul)" < = EMAIL ADDRESS REMOVED = >
>>> Subject: Re: [teitac-telecom] Telecommunications Working
>> Group- Draft
>>> 1 Template for 508 in WORD
>>> To: "TEITAC Telecommunications Subcommittee"
>>> < = EMAIL ADDRESS REMOVED = >
>>> Cc: = EMAIL ADDRESS REMOVED = , Creagan Tim
>>> < = EMAIL ADDRESS REMOVED = >
>>> Message-ID:
>>>
>>>
>>
> < = EMAIL ADDRESS REMOVED =
>>> m>
>>>
>>> Content-Type: text/plain; charset="us-ascii"
>>>
>>> Regarding the reference to "PSTN" versus "IP" in many of
>> the proposed
>>> requirements, I agree that IP telephones should be treated
>> differently
>>> but am concerned that describing the non-IP systems as
> "PSTN" will
>>> create a lot of confusion.
>>>
>>>
>>>
>>> The "PSTN" is the Public Switched Telephone Network. If asked to
>>> describe a PSTN telephony endpoint, I imagine that most telecom
>>> specialists would say it was an analog device that complies
>> with the
>>> FCC regulations that govern residential telephones. If
> we use this
>>> definition, I can't remember the last time I've seen a government
>>> procurement of telecom equipment that falls into this category.
>>>
>>>
>>>
>>> There are at least three different categories of non-IP wired
>>> telephones in common use today:
>>>
>>>
>>>
>>> Residential analog. (This is what most folks would classify as a
>>> "PSTN
>>> phone.")
>>>
>>>
>>>
>>> Enterprise analog. (The distinction between these phones and
>>> residential analog sets is that the enterprise sets
> connect to the
>>> PSTN via a PBX or switch that is owned by the enterprise. An
>>> important electrical distinction is that, unlike
> enterprise analog
>>> telephones, residential telephones are required to do
>> "automatic loop
>>> length compensation" to account for distance-related
> differences in
>>> electrical resistance and capacitance in the line between
> the phone
>>> and the associated central office. Another important
>> distinction is
>>> that many enterprise analog solutions are actually hybrid
>> analog/digital sets.
>>> The audio stream is carried as traditional analog,
> supplemented by
>>> digital signaling that, for example, controls the phone's
> display.)
>>>
>>>
>>>
>>> Enterprise digital. (This is what is purchased in the vast
>> majority
>>> of non-IP wired telephony procurements by the government.
>> All audio
>>> transmissions entering or leaving the phone are digitally
> encoded,
>>> typically using the G.711 algorithm that I described in a
> previous
>>> message. Signaling and call control is also digital,
>> typically using
>>> protocols that are proprietary to the individual manufacturers.)
>>>
>>>
>>>
>>> Wired residential analog systems, wired enterprise analog
>> systems, and
>>> wired enterprise digital systems are able to transmit Baudot TTY
>>> signals with 100% reliability. IP telephony is different.
>>>
>>>
>>>
>>> Depending on network characteristics, the mechanisms that
>> are used in
>>> order to transport voice signals within IP networks are
> not always
>>> suitable for transporting Baudot TTY tones. Common sources of
>>> impairment include packet loss and the use of
> voice-optimized audio
>>> compression algorithms, such as G.729. For this reason, a
>> traditional
>>> TTY device used in conjunction with an IP phone (for
>> example, via an
>>> acoustic coupler) is not always going to be reliable.
>>>
>>>
>>>
>>> The good news is that, although not yet in common use, there are
>>> international standards that describe how to transport text
>> and Baudot
>>> tones reliably on IP networks. In general, these
> techniques do not
>>> use the same audio encoding and transmission mechanisms
>> that are used
>>> for voice. I agree completely that the availability of these
>>> techniques, coupled with the inherent unreliability of Baudot TTY
>>> transmissions via the "voice channels" of IP telephone
>> networks, makes
>>> it essential that we treat IP telephony as a special case
>> in the Section 508 refresh.
>>>
>>>
>>>
>>> Getting back to the original topic of my message... We
> need a term
>>> other than PSTN to describe non-IP wired telephony. Ideally, it
>>> should be a term or description that would make sense to
>> someone who
>>> is not knowledgeable about telephone engineering. To start
>> the ball
>>> rolling, I suggest "wired analog and wired non-IP digital" as a
>>> substitute for PSTN. (I deliberately use the word
> "wired" because
>>> wireless devices have special characteristics that may need to be
>>> addressed separately.)
>>>
>>>
>>>
>>> -- Paul Michaelis
>>>
>>>
>>>
>>>
>>>
>>>
>>>

From: Gregg Vanderheiden
Date: Sun, Apr 01 2007 3:50 PM
Subject: Re: teitac-telecom, PSTN Reference

Hi Jim,



Oh, the point wasn't that one of the three categories wasn't covered by the
definition of E&IT. All three would be covered as you suggest.



The point was that there should be different requirements for the three
categories. (public analog PSTN, public packet/IP/SIP and other, closed
systems)



You have to have interoperability in telecom or you can't have guaranteed
calls. You can't guarantee that the two ends can connect.



o For Voice on IP there is G.711. All systems support it or convert
to it (which is the same as supporting it). they may support many other
format but they will support G.711 when they hit any external systems.



o There needs to be a similar requirement for text for example. But
it needs to be different in different systems.



In analog (PSTN) it needs to be TIA 825 Baudot (TTY). That is the only
standard for text that we have in analog telephone system.



In IP/SIP systems, the industry standard is T140 communicated by RFC 4103
or Text/t140.



There are other formats like (RFC 4351) audio/t140 (note that this is not
audio transmission but text transmitted as T/140 data just like text/t140
except that you mislabel the text data packets as audio data packets and
sort it out at the far end.) This is done to avoid using extra ports. It
works well when linking to PSTN. But again, if you send in RFC 4351 and the
other phone supports only RFC 4103 then the voice will work but not the
text. RFC 4351 is listed as an historical format and many oppose its use
in public systems because it involves mislabeling data so it can masquerade
as audio. It was originally designed for use in closed network IP links
within the PSTN system (which according to the recommendations below -
should be able to use what ever they want. Since they control both ends .

.

** You either have to require that all telecom support one format - or you
have to require that they all support them all.



There is no other way to guarantee that calls go through except if you put
all calls through gateways that support ALL formats. We talked to industry
about this and they said it was too much overhead to run all calls through
these and asked who would pay for them all. (we have proposed such a
method (called T-hybrid servers) for PSTN to IP network gateways.)



The third category is "all things that are part of a closed system". This
can be PBXs or whole government systems. As long as they all provide
quality accurate reliable methods to transport text they do not have to use
the PSTN or the IP/SIP standards internally. They would only need to
convert to one of the standards when they interfaced with the PSTN or public
IP/SIP networks.



Again - there is no problem offering other formats on the PSTN or public
IP/SIP networks. Turbo-code has been available for a long time on PSTN. If
the receiver can handle the format it is fine to use. But like all
Turbo-code TTYs (that also supports TIA 825 Baudot to fall back on it
Turbo-code isn't supported by the other TTY), everything has to support one
standard required format so they can communicate if they don't both support
some other format(s).





In summary,



1) we need to specify a single standard format for the PSTN and IP/SIP
public networks that everything must support. (We could require more than
one but that is requiring more than is needed).

- if there isn't one that everyone supports then there can
be no interoperability or guaranteed connections.

a) TIA 825 Baudot for analog phones

b) ITU T.140 and RFC 4103



2) we should have performance requirements for closed systems but we should
not require that they use any particular format internally. Requirements
would be something like.

a) It support the character set needed to express the languages
involved

b) That they transmit the text with less than 1% character error.

c) That they support mixing of text and audio

d) If packet based, that they support text and voice simultaneously in
both directions (4 channels).

e) Terminal technologies (analog or digital) need to either provide
built in text send and receive/display abilities or they need to provide a
means to connect an appropriate device that will allow this. (Connection can
be in parallel with terminal device). (NOTE: if closed systems us
proprietary transport methods and don't provide built in send &
receive/display then this needs to be handled carefully. )











Gregg

-- ------------------------------

Gregg C Vanderheiden Ph.D.







> -----Original Message-----

> From: = EMAIL ADDRESS REMOVED =

> [mailto: = EMAIL ADDRESS REMOVED = ] On Behalf Of

> Jim Tobias

> Sent: Saturday, March 31, 2007 8:19 PM

> To: 'TEITAC Telecommunications Subcommittee'

> Subject: Re: [teitac-telecom] teitac-telecom, PSTN Reference

>

> I don't get your point. Anything the feds use for voice

> communication, be it internal, external, private, public,

> gateway, intercom, wireless, CB, ... anything -- it's all

> E&IT, and thus covered. If a vendor uses a proprietary system

> from top to bottom, but it meets the accessibility

> requirements on its own and interoperates (looking only at

> accessibility) with all other systems that the procuring

> agency finds necessary, it's compliant. Am I missing

> something? As much as we may want the telecom industry to

> adhere to some non-proprietary standard, I don't think we can

> use 508 to make that happen.

>

> ***

> Jim Tobias

> Inclusive Technologies

> +1.732.441.0831 v/tty

> +1.908.907.2387 mobile

> skype jimtobias

>

>

> > -----Original Message-----

> > From: Gregg Vanderheiden [mailto: = EMAIL ADDRESS REMOVED = ]

> > Sent: Saturday, March 31, 2007 7:07 PM

> > To: 'TEITAC Telecommunications Subcommittee'

> > Subject: Re: [teitac-telecom] teitac-telecom, PSTN Reference

> >

> > Hi Tom

> >

> > Remember that there were three types of systems proposed.

> >

> > The Public Analog, the Public IP and all other closed systems.

> >

> > All of the government phones connect to the PSTN or emerging IP/SIP

> > systems.

> > If they didn't you couldn't make a call.

> >

> > Most of the government phones are part of a system though and only

> > connect

> > to the PSTN through gateways or call managers. Making a

> > call from one

> > phone to another inside an agency may not ever touch the PSTN. It

> > would

> > simply be phone to phone. Some of those phones use

> > different standards and

> > some use proprietary methods to communicate between phone

> and between

> > the phone and the call manager/server/gateway to the PSTN.

> >

> > The problem then breaks down into three parts.

> >

> >

> > 1) can the person with a disability use the terminal device

> > (phone) and/or can they connect any AT they need to it.

> >

> > 2) can the connection between the terminal device (phone) and the

> > public network (or between two phones not on the public

> > network) carry the voice and text and possibly video reliably and

> > accurately.

> >

> > 3) when the call hits the public phone system, is it (the

> voice, text

> > and possibly video) in the right format to travel reliably on the

> > network and to work with the devices (standard phones or AT) at the

> > other end.

> >

> > What will work on the PSTN is different from what will work on the

> > IP/SIP network. And, if the two ends done use the same protocol or

> > support at least one common 'universal'

> > format for voice/text/video then the call

> > cannot be completed. Hence the need for established

> > standards for both the

> > PSTN and the IP/SIP networks.

> >

> >

> >

> > Does this help?

> >

> >

> > Gregg

> > -- ------------------------------

> > Gregg C Vanderheiden Ph.D.

> >

> >