Answer confirmation on a Zap Channel


I am using Asterisk-1.4.2.

I am trying to make asterisk auto-dial an external number. Basically, I want Asterisk to dial a number and play an announcment as soon as the callee pics up.

With SIP phones, everything works fine, but with Zap channel, I was encountering the problem, that Asterisk would detect the Answer event as soon as the connection was made(and not wait for the callee to pick up the phone, as it does in the case of SIP phone).

I figured out that using c option in Dial would solve my problem. So, now Asterisk detects the Answer event, after the callee has picked up the phone, and pressed the pound(#) key.

The command I am using is

exten => 502,n,Dial(Zap/2c/9795190920#,gM(try),)

However, I do not want that the callee press the pound key, Instead, I want Asterisk to automatically play an annoucement as soon as the callee picks up the phone,( waiting for the callee to press the pound key is very inconvenient).i.e I want Asterisk to detect the answer event, without the pound key being pressed.

How can I possibly do this?

Will using NVLineDetect help?

Thanks for the help.



When you zap channel and from your discription of your problem I would guess you are using ALOG trunks not PRI ISDN, Is that correct ?

If it is then to get answer supervision on alog trunks is pretty much impossible. I would swap to ISDN or VOIP trunks as these do support Answer supervison.