We are using Asterisk 13.15.0 with PJSIP.
We use the Take Back and Transfer model to move certain callers off of our IVR to another server. This is simple to implement using the Asterisk Transfer() dialplan application and is supported by our carrier Twilio.
What I don’t know is how to detect the final NOTIFY message from Twilio carrying the sipfrag “200 OK” that tells us that a successful transfer has occurred. It was tempting to use the TRANSFERSTATUS channel variable but that only tells whether the initial SIP REFER request was successfully sent.
We would like to know what the final outcome of the Transfer is so that we can provide a failover route for any failed Transfers.
I really appreciate any suggestions!