On 1/23/07, Bruce Atherton <[EMAIL PROTECTED]> wrote: > I am trying to write a program that makes a SIP connection to a PBX and > asks the PBX to dial out on a PSTN line. Once someone answers, the > program plays a message to the person phoned to let them know about a > problem they need to fix. I'd like to make the program work with as many > PBXs as possible. > > My problem is that I don't want the PBX to respond "200 OK" to the > INVITE until the PSTN line has actually been picked up. In other words, > the SIP call status should be based on the PSTN call status. I'm not > worried about "180 Ringing" state as it is difficult to detect ringing > on the PSTN, but "200 OK" must wait for the voltage drop that indicates > a connection on the PSTN. > > The reason I need this is that otherwise, the program starts playing the > message about what needs fixing while the PSTN phone is still ringing. > Also, the program can never tell whether a call was received by someone > or not. So it doesn't know whether to go further with the call tree. > > Is there a standard way in SIP to accomplish this? Is there anything my > program can do to instruct a SIP-enabled PBX to make the SIP state > mirror the PSTN state the call is gatewayed to? Or is there something it > can watch for in its communications with the PBX that is independent of > the SIP call status, but will let it know when the PSTN line goes to a > connected state? > > If there is no standard way to accomplish this, then does anyone know > which PBXs can be configured to act this way? A generic solution would > be best, but if need be I'll deal with the most popular PBXs > individually. My guess is that PBXs which advertise that they can act as > both a SIP Proxy and a SIP Gateway are the ones that have the potential > to deal with call state in this way, but I'm finding it hard to find > information on the subject. > > I am really struggling to get a handle on how to deliver this > functionality. Any help is greatly appreciated, even if it is just > search terms I should be targeting for researching this. > _______________________________________________ > Sip-implementors mailing list > [email protected] > https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors >
Does the "100 'Trying'" message provide the functionality you're looking for? Aaron _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
