> -----Original Message----- > From: Eric Burger [mailto:[EMAIL PROTECTED] > Sent: Monday, October 15, 2007 7:49 AM > To: Christer Holmberg; Hadriel Kaplan > Cc: IETF SIP List > Subject: Unsolicited NOTIFY/INFO versus Solicited State Update > > A few times I have seen a comment stating the endpoint interested in > potentially receiving DTMF notifications may not know whether or not it > needs DTMF. As such, the endpoint would be forced to always issue a > SUBSCRIBE, even if it will not be interested in DTMF. > > Could someone please describe a scenario in which the endpoint does NOT > KNOW, a'priori, it will be interested in DTMF? > > All the ones I can think of, like supplemental dial digits, ACD, register > recall, and return to application are all known to the AS or Proxy driving > the interaction. > > What else is out there?
A PSTN gateway has no idea what the PSTN-side call goes to or came from. It may or may not need DTMF. That PSTN GW has to subscribe for every call if it (or the other end) doesn't do 2833, regardless if any DTMF get pressed. The same for a SIP-H.323 gateway, a Skype-SIP gateway, etc. (for H.323 in particular the probability of 2833 support is very low) And even for a SIP AS that knows it needs DTMF, for some applications a KPML model will be more efficient than INFO, for others less... much less. -hadriel _______________________________________________ Sip mailing list https://www1.ietf.org/mailman/listinfo/sip This list is for NEW development of the core SIP Protocol Use [EMAIL PROTECTED] for questions on current sip Use [EMAIL PROTECTED] for new developments on the application of sip
