[Asterisk-Users] PSTN->SIP->PSTN transfer problem

[Andre Ferreira]

Hi all

I have a rather odd problem that I hope somebody can shed some light on. I 
have a Asterisk server (1.0.7) that is connected to a Cisco 2600 router 
(c2600-is-mz.122-28a) fitted with an E1 card. The E1 is configured for QSig 
and is conencted to our local Ericsson MD110 which goes out to the PSTN. We 
have a DID range assigned to the E1 and can make and receive calls from/to 
SIP attached phones through this gateway setup.

The problem i have is with transfering calls. I can do supervised and 
unsupervised transfers from/to any of the IP phones behind Asterisk. I can 
also recieve a call from the Ericsson and transfer it to another IP phone 
without a problem. What I can't do is receive a call from the Ericsson on an 
IP phone and then transfer it back to another Ericsson extension or a PSTN 
number. Watching the call progress with Ethereal (really neat VIOP tracker 
in the latest version), I can see the call setup take place, the receiveing 
phone actually rings, but once I answer the receiving phone the call setup 
never completes and the trace shows a continuous stream of invites, acks and 
ok's. Here is a sample:

SIP      Request: ACK sip:62153 at 10.12.3.189:5060
SIP/SDP  Request: INVITE sip:62153 at 10.12.3.189:5060, with session 
description
SIP/SDP  Request: INVITE sip:anonymous at 10.12.3.189:5060, with session 
description
SIP/SDP  Status: 200 OK, with session description
SIP      Request: ACK sip:62153 at 10.12.3.189:5060
SIP/SDP  Status: 200 OK, with session description
SIP      Request: ACK sip:anonymous at 10.12.3.189:5060

The digit 6 is the truck access number to route out to the Ericsson with the 
2153 being an Ericsson extension. The anonymous is being received from the 
Ericsson instead of CLI at the moment (could this be a problem??)

This sequence of packets repeat continually until one of the phones hangs 
up.

My current two suspects are the Cisco gateway that maybe does not support 
transfer, but version 12.2x code should do and the Ericsson that is not 
communicating correctly with the Cisco.

As an aside, call forwarding from my Cisco 7960 to an Ericsson extension 
exibits the same behaviour, but that can be expected I suppose (??)

Any ideas would me most welcome.

Thanks
Andre

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