On Fri, Oct 02, 2009 at 04:22:55PM -0400, Dale Worley wrote: > On Thu, 2009-10-01 at 10:37 +0200, DE CLERCQ Johan wrote: > > As we all know, in ISDN you can detect when you go to a voicemailbox of > > a cellular line by looking for the PROGRES message as defined in Q.931. > > There is no good way to do this in SIP. However, an answering automaton > "should" identify itself with the "automata" media feature tag on its > Contact header: > > Contact: <sip:u...@pc.example.com>;automata > > See RFC 3840.
Even the inclusion of this tag isn't fool proof. Consider the case of user with voicemail screening. The call is initially directed to an automata but a human listening in to the recording decides to take the call. A human has answered, but some filtering was applied. Or a caller interrogation service that collects information about the caller for users who refuse calls from private numbers. This would also be initially answered by an automata, but could ultimately be answered by a human. If you are solely looking for whether you were directed to voicemail, I would look more into the diversion headers and the information you get there. They will tell you the reason the call was forwarded where it was going before. Have a look at http://tools.ietf.org/html/draft-levy-sip-diversion-10 David _______________________________________________ Sip-implementors mailing list Sip-implementors@lists.cs.columbia.edu https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
