Getting Answer event on SIP channel

Hello All
I am using trixbox 2.0 and account at as trunk for making outbound calls to PSTN numbers in US. I am making a system to broadcast the message by any user to all the numbers chosen by him from his contacts.
Now what is going on that when I place the call from PHP code using Originate command of Manager API after few seconds of placing the call the system assumes it as answered and starts playing my message and when the callee pickup the phone, the message is already half the way gone or on “Good bye”.
So I want to know whether there is some way to have a answer supervision on SIP channel to get the real time of pickup the phone. Please help me in this context. If anybody need some config or log information for investigation, I can provide it. Thanks in Advance for help.


SIP does have answer supervision. If SIPphone is telling you the call is answered (look on your CLI) before it actually is, they are doing something wrong. Every provide that I’ve ever used (I haven’t used SIPphone) sends either ringing or early audio progress ringing and only considers the channel answered once the remote party answers.