Thread Subject: RFC 4103 for real time text - why RTP
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From: Gunnar Hellström
Date: Wed, May 23 2007 3:45 PM
Subject: RFC 4103 for real time text - why RTP
Concern 2 about 1194.23(b) : In today?s meeting, there was a question on why
the RTP protocol was selected for transmission of real-time text in SIP
calls with RFC 4103 for text. RTP may be experienced to be complex.
Answer: There are thorough reasons behind the choice.
The prime reason is to treat the real-time text medium as similar as
possible to other media in the call. Other media use RTP. By using it for
real-time text as well, the following is achieved: Least complexity: No
extra basic protocol needed. Same transmission route as voice and optionally
video. Least risk to get stuck in network elements. No extra servers along
the route. One important reason is also that until very recently there was
no standard for including anything else than RTP media in a SIP call. Now it
is possible on paper to use TCP for media in SIP calls, but many
implementations of network components still do not support this new
standard. TCP would also introduce more overhead. Thus, we keep to the basic
and least complex by using the Real Time Protocol, RTP.
Regards
Gunnar Hellström
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Gunnar Hellström
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