[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[AVT] RE: [Sip-implementors] DTMF interoperability: In-band, RFC 2833 or SIP INFO
Hi Murat,
Note that the in-band method for DTMF tones transfer through the VoIP
network has additional significant drawback: the classification of DTMF
digits which are received in-band is not reliable when compressed voice
codec is used (different than G.711).
Regards
---------------------------------------
Meir Leshem
System Engineer
Veraz Networks
---------------------------------------
-----Original Message-----
From: sip-implementors-bounces at lists.cs.columbia.edu
[mailto:sip-implementors-bounces at lists.cs.columbia.edu] On Behalf Of
Murat Artun
Sent: Wednesday, June 20, 2007 11:45 AM
To: avt at ietf.org; sip-implementors at cs.columbia.edu
Subject: [Sip-implementors] DTMF interoperability: In-band,RFC 2833 or
SIP INFO
Hello all,
I want to ask about the interoperability issues for DTMF sending.
There exist three ways for DTMF sending: In-band (I use this term
meaning in audio as a voice data), RFC 2833 (currently 4733 obsoletes,
but no change to previous procedure exists) and SIP INFO.
Among these three ways, I know that only RFC 2833 is announced in the
SDP of a VoIP application when it is ready to receive DTMF events as
RFC 2833 packets.
I have a few points to be clarified in the sense of interoperability
issues:
- Is it preferred that DTMF is also sent in-band and as SIP INFO when
the remote VoIP application announces that it is ready to receive RFC
2833 packets?
- What if the remote VoIP application does not announce that it is
ready to receive RFC 2833 packets? Which method should be preferred,
In-band or SIP INFO, or both for reliability purposes?
- I have observed that sending DTMF as RFC 2833 packets is mostly
preferred considering that sending DTMF In-band requires the remote
VoIP application to perform tone detection in RTP level which requires
considerable processing overhead as RFC also states. Is there a known
issue about SIP INFO method for DTMF sending?
Thanks in advice...
--
M u r at A r t u n, MSc.
Design Engineer
_______________________________________________
Sip-implementors mailing list
Sip-implementors at lists.cs.columbia.edu
https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
_______________________________________________
Audio/Video Transport Working Group
avt at ietf.org
https://www1.ietf.org/mailman/listinfo/avt