Jeff,
There are several places where this can fall down. Some of the things I would check.
1. Use DNA on the CUCM side to get an idea of what the call flow should be from a CUCM config perspective. You can access DNA portal here: https://:8443/dna. You will need to enable the Cisco Dialed Number Analyzer Server. Recommend you do this on the pub only. You can analize a call from a phone perspective. The interface is pretty intuitive. You will see call transformations in the resulting analysis. Check that and look for any anomolies.
2. Debug SIP messages from CUCM. If the SIP trunk is a direct path (i.e. no UBE) then you can enable Detailed tracing on the CallManager service. You can toggle the options to include "Enable SIP Call Processing Trace". De-select other options if you want cleaner output.
3. In tandem to or instead of #2, you may want to look at SIP session trace in RTMT (see:
http://www.ucguerrilla.com/2012/03/cisco-cucm-rtmt-session-trace.html)
With Test 1 you are looking at what the config says should happen. With items 2 and 3 you are looking at the SIP messages CUCM sends to your PBX. Look at the Invite messages and the various to/from header fields. You want to see if the problem is introduced at the CUCM-side. If Test 2 and 3 show that CUCM is sending the right headers then look at your PBX configuration.
If you are using CUBE then you can use debug ccsip messages on the CUBE device to see ingress/egress SIP messages. Look for any issues being inserted here. If you have garbage in from CUCM then diagnose CUCM. If you have garbage out then look at CUBE config. If you are good in and out, look at your PBX.
In regards to external mask and digit transformation with SIP trunks and the CUCM dial plan analysis process. There is a priority order applied. If transformations occur at a higher priority level, all other transformations are ignored.
Application, in priority order:
1. Transformations on the trunk for calling/called are applied. This is whether transforms are directly configured or if they are applied by way of transformation CSS. Check the config here. NOTE: In test #1 above, it used to be that transformation patterns were not shown by DNA. Not sure if that has been fixed yet.
2. Transformations on any RouteList / Route Group are applied. Go to the route list and look at Route Groups. It is very common for people to set the Route Group to something like "Off" for external mask presentation. Which would override anything on a route pattern level.
3. Route Pattern transformations.
HTH.
Regards,
Bill (http://ucguerrilla.com)
