[Asterisk-Users] odd transfer behavior

[Jon Lewis]

Using Asterisk 1.0.x, I'm seeing the following when trying to allow the 
called party to transfer calls:

sip phone --> asteriskC --IAX2--> asteriskA --ZAP--> PSTN --> called party

i.e. a sip user on server asteriskC places a call, which is sent to the 
PSTN via IAX2 to asteriskA.  asteriskC includes the t flag in its 
Dial(IAX2/...).  This case works, though I found that the called party can 
only transfer calls to extensions asteriskC makes accessible to 
asteriskA via context= in the iax.conf entry...which I suppose makes 
sense.

However, if the call flow is:

asteriskB --IAX2--> asteriskC --IAX2--> asteriskA --ZAP--> PSTN -> called party

i.e. a call comes into asteriskC via IAX2, and is either:

a) answered by a SIP client who transfers the call to an exten that dials 
out (with t flag) via IAX2 to asteriskA and the PSTN

b) is Answered in the dialplan and then sent via Goto to an exten that
dials out (with t flag) to the PSTN via IAX2 to asteriskA.

In these cases, the called party cannot do a # transfer.  I found 
asteriskC could only recoginze a #transfer attempt by the called party if 
I forced a mismatch in codecs between the incoming and outgoing IAX.  Even 
with that, though, I can't get #transfer to work as the called party seems 
to have no context.  i.e.

     -- Operating with different codecs, can't native bridge...
     -- Playing 'pbx-transfer' (language 'en')
     -- Unable to find extension '4' in context ''

As soon as I dial any digit after #, asteriskC errors saying the extension 
is not found in a null context.

Is what I'm trying to setup possible on a server with no direct PSTN 
access?  All PSTN origination and termination is done via IAX2.

I've just tested this with the recently released version 1.2 of Asterisk 
on asteriskC, and the behavior is largely unchanged.  1.2 seems to do a 
better job of noticing the # even while it says it's natively bridged the 
calls, but I still get an Unable to find extension '<first digit pressed>' 
in context '' suggesting that the called party trying to do a #transfer 
has no context.

----------------------------------------------------------------------
  Jon Lewis                   |  I route
  Senior Network Engineer     |  therefore you are
  Atlantic Net                |
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