Thread Subject: Re: (no subject)

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From: Paul E. Jones
Date: Tue, May 15 2007 2:40 PM

Gregg,



I apologize, but I'm not up to speed on the various specs that are currently
under consideration by this group, having just joined the list. However, if
the specification covers communication between the enterprise and the
service provider, then TIA 1001 would fall into scope. Whether it's
preferred or not is another matter.



TIA 1001 was drafted because there was an industry concern with the reliable
transport of TTY signals over IP networks. In a network with just 1% packet
loss, the character error rate (CER) would be 9% (assuming random packet
loss). My IP connectivity is actually pretty good, so as long as I'm
calling within the US, I see virtually no packet loss. However, there are
times where the network is congested and all it takes is 0.12% packet loss
to see a 1% CER. (You might find this useful:
http://www.packetizer.com/voip/toip/cercalc.html) In short, it takes only a
little packet loss to make my 911 calls problematic.



The alternative to using TIA 1001 to support transport of legacy TTY signals
over IP, of course, is to use VBD along with FEC or redundancy, but then
there bandwidth utilization increases to 106Kbps to 160Kbps (or more) for a
single TTY call. This seems to go against the industry preference I see in
North America today for lower bit-rate codecs like G.79 (~ 24Kbps including
overhead) between the enterprise and service provider.



Paul



From: = EMAIL ADDRESS REMOVED =
[mailto: = EMAIL ADDRESS REMOVED = ] On Behalf Of Gregg
Vanderheiden
Sent: Tuesday, May 15, 2007 2:39 PM
To: 'TEITAC Telecommunications Subcommittee'
Subject: Re: [teitac-telecom] (no subject)



Hmmm



Interesting. Sort of w mini-gateway to gateway application.



Paul this would fall into our "within a system" category and I am suggesting
that we make no specifications for specific technologies within people's
(company's) systems. Only when out side of the system. (Inside we would
have only performance specs).




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





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From: = EMAIL ADDRESS REMOVED =
[mailto: = EMAIL ADDRESS REMOVED = ] On Behalf Of Paul E. Jones
Sent: Tuesday, May 15, 2007 1:25 PM
To: 'TEITAC Telecommunications Subcommittee'
Subject: Re: [teitac-telecom] (no subject)

Gregg,



I agree with not including the reference for TIA 1001 as a definition of a
TTY. However, I should clarify that TIA 1001 is not defined for service
provider use exclusively. Within an enterprise, a TTY device might be
connected to an analog phone jack that leads to an enterprise gateway device
in the wiring closet that uses TIA 1001.



Paul





From: = EMAIL ADDRESS REMOVED =
[mailto: = EMAIL ADDRESS REMOVED = ] On Behalf Of Gregg
Vanderheiden
Sent: Monday, May 14, 2007 11:47 AM
To: 'TEITAC Telecommunications Subcommittee'
Subject: Re: [teitac-telecom] (no subject)



Agree



We need to split this definition between TTY and other Real-time text
approaches.



I thought there was a bunch of discussion on this already somewhere.



Ah yes.. there was. Including the comment that TIA-1001 is a standard
for carriers - not for terminal devices. (it is a standard for sending
signals from one PSTN link to another using a closed IP link in the middle.




Unless the government is buying its own carriers or putting regulations on
carriers we shouldn't be using TIA-1001.

RFC-4103 is the one for terminals.




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





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From: = EMAIL ADDRESS REMOVED =
[mailto: = EMAIL ADDRESS REMOVED = ] On Behalf Of Brooner
Mary-AMB004
Sent: Monday, May 14, 2007 9:52 AM
To: = EMAIL ADDRESS REMOVED =
Subject: [teitac-telecom] (no subject)

The Subpart A working group has a definition of TTY which is currently
defined ( <http://teitac.org/wiki/Subpart_A_Report_2007-04-18>
http://teitac.org/wiki/Subpart_A_Report_2007-04-18) as follows:



An abbreviation for teletypewriter. Machinery or equipment that employs
interactive text based communications through the transmission of coded
signals across the telephone network. As used in this part, the term TTY
includes text-to-text communications along with voice and text intermixed
communications such as voice carry over and hearing carry over. TTYs may
include, for example, devices known as TDDs (telecommunication display
devices or telecommunication devices for deaf persons) or computers with
special modems. TTYs are also called text telephones.

There is a conversation in TIA that this may be a too broad definition and
might include non-standard proprietary coding or really any text messaging
(IM) service one could imagine. A possible modification of the definition is
below. I would like for the Telecom WG to discuss this in today's call.

An abbreviation for teletypewriter. Machinery or equipment that employs
interactive text based communications through the transmission of coded
signals across the public switched telephone network in compliance with
TIA-825-A, A Frequency Shift Keyed Modem For Use On The Public Switched
Telephone Network; [or across an IP network in compliance with TIA-1001,
Transport of TIA-825-A Signals over IP Networks.]



Mary Brooner, Telecom WG Co-chair

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