How to receive sip messages (181 for example) call forwarding

Hi @all,
I’ve been developing an IVR for a no credit voice portal (for carriers), and now I need to receive an event or information about a sip massage that seems to be delivered to asterisk during the communications but I could not find a way to receive it. The message is a sip message 181 that indicate that the call is being forwarded and I also want to get headers that came out of the invite header. Did any one can point me a solution or information that helps me to solve this.

As the last options, I think I can help to develop something like this to integrate to the asterisk code.

Thanks
Flavio Magacho

chan_sip has built in support for 181, which is reflected in the mechanisms described in https://wiki.asterisk.org/wiki/display/AST/Manipulating+Party+ID+Information

I assume the same is true of pjsip.

There is no mechanism to access arbitrary fields from the response.

Also note that 181 is sent unreliably, unless, possible, you enable PRACK.