Hi, S. Manivannan > I get some information from this RFC, but I need call flow involved in > FAX over SIP. A call flow is only informative.
Meir Leshem > As far as I know, draft-ietf-sipping-realtimefax-01 (which is expired > of > course) is the de-facto standard for negotiation of fax handling (T.38 > and fallback to G.711) in SIP. draft-ietf-sipping-realtimefax-01 is dead, RIP. As one of the original authors of the sipping draft, I guess I should chime in. This old draft was put together back in 1999 when voip gateways started to implement t.38 fax and it helped in the first sipit where we tested fax way back then. The itu specs were also not stable and it helped debug issues and get some interop going. But this is now over and the draft should not be used as a reference: it was a work-in-progress. It was rightly decided by the sipping chairs at the time that the draft was about SDP attributes for t38 fax and then RFC 3362 was published, and then rfc4612. That said, the old draft is still used by many folks to understand that you got to start with an audio session, wait for the fax whistling and some specific triggers to perform tone detection then switch to an appropriate codec (g711 fallback or switch to another one). Note that with super G3 fax machines, modem/voice band data, T.38v3 and V.152, implementers have a couple more options to transport fax/mode calls reliably and it's gotten a little bit more interesting. Also, in some networks, g711 just works fine. Colin wrote: > RFC 4612? Yes. This adds mime types for t.38 over rtp; many implementations still use udptl. It's been a while I moved away from this but the itu Recommendation should be reference spec (annex D?). Jean-Francois. > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:sip- > [EMAIL PROTECTED] On Behalf Of Meir Leshem > Sent: Thursday, June 28, 2007 8:45 AM > To: Manivannan S, TLS-Chennai; Gaurav Kheterpal; sip- > [EMAIL PROTECTED]; [EMAIL PROTECTED] > Subject: Re: [Sip-implementors] SIP and FAX > > Hi, > > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of > Manivannan S, TLS-Chennai > Sent: Thursday, June 28, 2007 4:13 PM > To: Gaurav Kheterpal; [EMAIL PROTECTED]; > [EMAIL PROTECTED] > Subject: Re: [Sip-implementors] SIP and FAX > > Thanks Gaurav, > > I get some information from this RFC, but I need call flow involved in > FAX over SIP. I have found a > draft(draft-ietf-sipping-realtimefax-01.txt), but it is expired. Any > latest RFC/draft explaining the call flow of FAX t.38 over SIP. > > Thanks, > S. Manivannan > > -----Original Message----- > From: Gaurav Kheterpal [mailto:[EMAIL PROTECTED] > Sent: Thursday, June 28, 2007 4:20 PM > To: Manivannan S, TLS-Chennai; [EMAIL PROTECTED]; > [EMAIL PROTECTED] > Subject: RE: [Sip-implementors] SIP and FAX > > You can refer to:- > > * RFC 4612 - Real-Time Facsimile (T.38) - audio/t38 MIME Sub-type > Registration > > * http://www.iana.org/assignments/sdp-parameters > > * ITU-T T.38 Annexure D, Section 9 > > * draft-andreasen-mmusic-sdp-capability-negotiation-reqts-00 - SDP > Capability Negotiation: Requirements and Review of Existing Work > > Regards, > Gaurav > > > -----Original Message----- > > From: [EMAIL PROTECTED] [mailto:sip- > > [EMAIL PROTECTED] On Behalf Of Manivannan > S, > > > TLS-Chennai > > Sent: Thursday, June 28, 2007 2:45 PM > > To: [EMAIL PROTECTED]; [EMAIL PROTECTED]; Manivannan S, > > TLS- Chennai > > Subject: [Sip-implementors] SIP and FAX > > > > > > Hi all, > > > > > > > > Could anybody tell me which latest RFC/draft is explaining FAX T.38 > > over SIP and SDP? I have googled and found only expired drafts. _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
