[Asterisk-Users] call forwarding without answer

[Andrew C. Brown]

Axel Bodemann wrote:
> Hi,
> 
> I want to forward a incoming SIP call to an external phone number. Is it
> possible to do this without answering the call first? I think there must
> be a solution like this:
> 
> - incoming call (SIP) -> Asterisk PBX
> - PBX trys to establish a channel to external number (PSTN)
> - SIP caller gets a free or busy signal depending on the status of the
> external number (without charging the SIP caller, because the caller can
> come in through the PSTN network, e.g. Sipgate)
> - if external number picks up the line -> the SIP channel and the PSTN
> channels are connected (charging both lines starts)
> 
> Is this possible and what have I to do, to get it working?

This sounded interesting, so I tried it last night.

The challenge is figuring out how to ring and get call progress
information on the outgoing Zap channel before deciding whether or not
to brige the SIP call.

The Dial command dials out the outgoing channel and if answered performs
a bridge with the preexisting inbound channel. The problem I had was
that it was bridging the connection whether anyone answered or not.

So does anyone know of a way to dial out without bridging an existing
channel?

I'm not sure it matters though. I think my ITSP charged me as soon a the
call was placed, not after it was answered.