[asterisk-dev] ISDN gurus - getting isdn call progress ??

[Kevin P. Fleming]

Julian Lyndon-Smith wrote:
> we have an ISDN-30 Euro connection. When dialling out is it possible to
> stop a call when it is about to start ringing ? (i.e is there an ISDN
> message that says "yup, this is a valid number, starting to ring now" ?)

The message tells you that the call has _begun_ ringing, not that the
call is being placed. I don't know of any signaling that you could use
just to verify that numbers are dialable, without actually placing the
calls and then dropping them.