[AVT] RE: Last Call: 'RTP Payload for DTMF Digits, Telephony ones and T elephony Signals' to Proposed Standard

[Sasha Vainshtein <[e-mail]>]

Hi all,
I'd like to raise the following issue with draft-ietf-avt-rfc2833bis-12.txt.

Original RFC 2833 has defined encoding of a wide range of telephony events
including ABCD (a.k.a. CAS) signaling events. In particular, a contiguous
block of 16 code
points (from 144 to 159) has been allocated for 16 ABCD signals (ranging
from 0 to 15
accordingly).

Please note that this encoding is used in in draft-ietf-pwe3-cesopsn-06.txt
to carry structure-aware TDM services with ABCD signaling over pseudo-wires.

RFC 2833 did not set up any IANA registry for the tepephony events,
but has used the code points from 0 up to (and including) 173 
(of the 255 available code points).

Looking at draft-ietf-avt-rfc2833bis-12.txt I've found that:

- this draft, when approved, would OBSOLETE RFC 2833
- it sets up a new IANA registry for code points representing
  DTMF tones and telephony events BUT populates this registry 
  only with 16 code points for the DTMF tones. The rest of the code 
  points defined in the original RFC 2833 are essentially INVALIDATED, 
  and IANA is free to re-allocate them as it sees fit.

IMHO this could potentially create multiple backward compatibility
issues, especialy if, as in the case of ABCD signals, contiguous
blocks of code points are desirable for specific applications.

Hence I suggest to RETAIN all the code points allocated in the original 
RFC 2833 in the mew IANA registry. This would prevent any backward 
compatibility issues while still leaving 83 free code points (174 to 255) 
for IANA to distribute. If this is not enough, some "unused code point 
reclamation process" could be run. 

IMHO this could be achieved by incorporating the relevant parts of the 
original RFC 2833 into the new draft.

Hopefully these notes will be useful.

Regards,
       Sasha Vainshtein

> -----Original Message-----
> From: The IESG [mailto:[e-mail]]
> Sent: Thursday, April 06, 2006 9:30 PM
> To: IETF-Announce
> Cc: [e-mail]
> Subject: Last Call: 'RTP Payload for DTMF Digits, Telephony 
> Tones and Telephony Signals' to Proposed Standard 
> 
> 
> The IESG has received a request from the Audio/Video 
> Transport WG to consider 
> the following documents:
> 
> - 'RTP Payload for DTMF Digits, Telephony Tones and Telephony 
> Signals '
> <draft-ietf-avt-rfc2833bis-12.txt> as a Proposed Standard
> - 'Definition of Events For Modem, FAX, and Text Telephony Signals '
> <draft-ietf-avt-rfc2833bisdata-06.txt> as a Proposed Standard
> 
> The IESG plans to make a decision in the next few weeks, and solicits
> final comments on this action. Please send any comments to the
> [e-mail] or [e-mail] mailing lists by 2006-05-04.
> 
> The file can be obtained via
> http://www.ietf.org/internet-drafts/draft-ietf-avt-rfc2833bis-12.txt
> http://www.ietf.org/internet-drafts/draft-ietf-avt-rfc2833bisd
ata-06.txt

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