Subject: [AVT] SG16 feedback on draft-ietf-avt-2833bisdata-02.txt

From: "Tom-PT Taylor" <[email-masked]>
Date: Tue, 02 Aug 2005 03:11:53 -0400

I gave a brief presentation on draft-ietf-avt-2833bisdata-02.txt to the 
modem people (Question 11) at ITU-T Study Group 16 last week.  (Slides 
available on request.)  They provided some useful immediate feedback, 
and may provide more when they get a chance to read the document.  They 
may reopen some of the V.15x specs. to include the new events defined in 
the I-D once it achieves RFC status.

The one substantive item people should know about now relates to the 
definition of the phase change events (ANS and /ANS, etc.).  Like us, 
they recognized an ambiguity in the original definition of those events. 
  They came to a different conclusion than the I-D.  The I-D has ANS 
altternating with /ANS at every phase change.  SG16 has instead put the 
burden on the receiver.  The sender reports ANS until a phase change is 
detected, and from then on reports /ANS continuously.  It is up to the 
receiver to play out phase changes at the required 450 ms intervals 
until the tone ceases.

This seems logical and robust, and has been written into V.151 (I 
think).  I propose to change the I-D to use the same procedure.

Tom Taylor

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