How to tell where a call is ringing in UCMA

Lately I’ve been spending a lot of time looking at “forking,” the process where a call (audio, IM, video, whatever) to a user is sent to all devices where that user is logged into Lync, and various ways to handle it in UCMA. A while back, I described how you can look at the SIP headers in the response when an outgoing call is answered to find out if, for example, a voicemail box answered the call. By looking at “provisional responses,” you can get details like this before the call is even answered, while it’s still “ringing” to the user’s various endpoints. Continue reading “How to tell where a call is ringing in UCMA” »