Calls will not transfer from SIP Trunk to MGCP gateway

Unanswered Question
Jul 13th, 2010

Hello All,

I have a UCM version 8.02 utilizing an internal SIP Trunk to an IVR (server).  The SIP Trunk functionality works well to the IVR, but if I initiate a transfer from the IVR to an outside number the call fails.  The call from the IVR utilizing a SIP trunk attempts to transfer to my 2811 voice gateway configured as MGCP.  The 2811 has 2 PRI trunks connected to a CO simulator (Hammer), which through scripting will answer the calls.  I can make an outbound call through the PRI Trunk group from the IVR, IP phone or SIP phone connected to the UCM but if I try to initiate a call transfer from the IVR using the SIP trunk, the call fails.

Here is the strange part, if I connect the UCM and IVR  to an H.323 gateway instead of the MGCP gateway the call transfer works like a champ.

This is a Lab environment so there is no Calling Search Space setup.

I'm guessing there is a config issue with the 2811?  But not sure on that.

Any help would be greatly appreciated.

Thank you...Frank

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Marcos Assakawa Sat, 07/17/2010 - 13:08

Hi Frank, It is difficult to know exactly what is the problem without traces, but I would make sure that the number IVR is sending the correct number to match the route pattern and route the call to the MGCP Gateway.  If you collect the CCM traces, I would be able to assist reading them.  I hope this helps,  Marcos

fkramarski Wed, 08/04/2010 - 07:59

Hey Marcos,

Thank you for the reply.

The IVR can successfully make an outbound call using the route pattern and out the MGCP gateway, but if a transfer is attempted it fails.  If I connect the UCM to an H.323 (the only thing changing being the gateway) the call transfers like a champ.  It is only if I use the MGCP gateway that the transfer fails.

I have attached the 2811 MGCP config and some trace files for you to look at.  I'm leaning towards a config issue with the 2811 but I am not an expert with gateway configurations.

Let me know if you have any other questions.

Thanx...Frank

Marcos Assakawa Wed, 08/04/2010 - 08:29

Hi Frank, I checked the gateway configuration and it looks fine. Looking into the CCM traces, I can see only SIP messages, but I don't see the MGCP messages and other things. Could you do me a favor. Go to the trace configuration page for CCM, set to default and then change level to detailed. Place a test call with transfer and let it failed. Collect the CCM traces again and update here and I will review and provide an update. I don't think that it is a GW issue, but rather some kind of interoperability betwee MGCP GW and SIP Trunk. There very little configuration on the CUCM. If the GW is registered to another node, please collect the CCM traces for the other node as well. Thanks, Marcos

fkramarski Wed, 09/01/2010 - 12:58

Hey Marcos,

Here are the trace files as requested.  I have also included the Wire Shark traces from the calling device and the SIP trunk endpoint.

Thank you again for the asistance and please let me know if you have any questions.

Thanx...Frank

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