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[chawkihammoud at yahoo...]

Hello everyone:


I have a problem where Asterisk need to make a sip outbound call and detect the Ring back tone or audio announcement before "answer". Asterisk need to avoid calling expensive rate premium numbers which have no pattern to differentiate them from normal numbers. When Such numbers are dialed, an audio announcement warn the customer about its expensive rate. At this time, Asterisk needs to detect this audio and hangup. Another way, is to detect the time when the channel receive ring back tone, if it it took certain period of time to start ringing, then it is a premium number and Asterisk need to hangup.


I searched a lot on this topic and I found out that all Asterisk dial plan starts when the channel is answered. I am not aware of any module in the dial plan that provide any information about the sip call status before "answer".




Thanks in advance