[Asterisk-Dev] PRI rejecting call without B channel

[Peter Svensson]

On Fri, 30 Jul 2004, Kevin P. Fleming wrote:

> > A little question... Is it possible using Aserisk to reject an incoming
> > call with a Hangup and a PRI_CAUSE (like fast busy) without actually
> > using a B channel, only at the D channel level?
> 
> Unless I'm mistaken B channels are never involved until Asterisk accepts 
> and answers the call. Prior to that point all communication related to 
> the call is just signalling on the D channel.

Isn't the B channel allocated by the SETUP call in isdn?

The audio channel from the b subscriber to the a subscriber is open (can
be opened?) before the b subscriber sends ANSWER. (I think it is opened
when sending PROCEEDING). You can play customized busy messages etc
without the a subscriber having to pay for the call.

Peter