[asterisk-users] QSIG transfer of calls away from Asterisk?

Matthew Fredrickson creslin at digium.com
Mon Jun 2 13:38:04 CDT 2008


Tony Mountifield wrote:
> I have a question concerning an Asterisk box connected to another
> (non-Asterisk) PBX using QSIG signalling over an E1 connection.
> 
> Certain extension numbers of the external PBX are routed to the
> Asterisk box, which in turn routes calls to its own extension phones.
> Dialplan routing is also in place so that users of those phones can
> also make calls routed over the E1 to extensions of the external PBX.
> 
> I think that if an incoming call (PBX->Asterisk) is then transferred
> to an external extension, the call continues to pass through the
> Asterisk box, consuming two B-channels on the E1.
> 
> Is it possible (a) in the QSIG protocol and (b) in the Asterisk
> implementation of it, to arrange it so that a transfer such as
> described above causes the call to revert back to being handled
> completely by the external PBX, and release the two B-channels?

a.) Yes, it is possible in the protocol.

b.) With the most recent version of libpri there is support for this.  I 
have heard mixed success with it, so your mileage may vary.  You simply 
need to have both channels be present on the same PRI, your switchtype 
must be Q.SIG, you must have transfer=yes for both channels involved (in 
zapata.conf) and you must also not be using any Dial() command flags 
that require monitoring of media (HhTt, and a few others) since it is 
accomplished via the native bridging code.

-- 
Matthew Fredrickson
Software/Firmware Engineer
Digium, Inc.



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