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: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Murat Artun Sent: Wednesday, June 20, 2007 11:45 AM To: [EMAIL PROTECTED]; [EMAIL PROTECTED] 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 [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
