CUCM incorrectly pre-appending outbound calling party mask with 91

[Networkgrouppch]

Running CUCM 11.0.1.  We have a fax server connecting to CUCM via SIP trunk.  CUCM is connected to PSTN via H.323 gateways. The only problem is with the outbound calling party's mask from the fax server. Somewhere along the line, callmanager tacks on 91 to the beginning of the calling party mask, prior to sending it out to PSTN.  The transmissions still complete, but the receiving parties get incorrect callback number info.  

Does anyone have an idea of where something like this could be configured to happen?

[Manish Gogna]

On CUCM you can check the Translation pattern, Route pattern/list/group to see if any Calling party transformations have been applied.

Manish

[Networkgrouppch]

Thanks Manish, but there aren't any translation patterns nor route patterns/list/groups in our cluster that are set to prepend 91 to calling party masks.  I'm now looking into the possibility that the CUCM SIP trunk config may have something to do with it.

[Dennis Mink]

Run Dialed Number analyzer under cucm serviceability tools, and emulate the call.

[Networkgrouppch]

Unfortunately, the DNA doesn't show the external (calling party) mask being translated at all.  I ran wireshark on the fax server interface, that connects to CUCM, and verified that it is indeed sending the correct calling party info, without the prepended 91. I assume that the problem likely lies somewhere within the CUCM SIP trunk config.