Cisco CUCM - changing caller ID on calling the PSTN

I am trying to make calls from one phone number appear as another phone number when they go to the PSTN. I thought I would be able to do that using External Phone Number Mask. But it seems to not be working how I'd hoped. Let's say I have extension 4501 and the DID is 650-555-4501. When the person at this phone calls to the PSTN I would like the ANI to be 650-555-4502. Would I accomplish that using the External Phone Number Mask and if yes what all would I enter in there? Or would I alter this somewhere else? At the gateway? Thank you.
amigan_99Network EngineerAsked:
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See if in the route group or route list if use callers external number mask is checked
amigan_99Network EngineerAuthor Commented:
I checked the relevant Route List and note the section with Calling Party Transformations. It's set to "Default" - need to trace that back. Perhaps for this one call I should create his own route list and set Calling Party Transformation Mask to the number I want to go out and set the item above that to off?
amigan_99Network EngineerAuthor Commented:
And for the device itself outbound looks like this ...
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José MéndezCommented:
Route Patterns have the option to apply the External Phone Number mask if any, or apply a fixed calling party for every outbound call.

I suggest using the DNA tool to understand a bit better what is happening.

ALso, if you are extending this call to a H.323 gateway, there might be additional calling number manipulations happening there.
amigan_99Network EngineerAuthor Commented:
Thanksk WB. I'm sending it to a SIP trunk to an ISR (which in turn has a SIP trunk to the PSTN carrier. The trick is that I just want to alter the calling number for this one phone/line. It's a long story as to why - but it revolves around some deficiencies in MRA/Expressway. I'm trying to kludge a solution together for a VIP.
José MéndezCommented:
So you will need to create a separate dialplan that only this VIP can access by his special CSS privileges, this dialplan is acollection of route patterns that modify the calling number in this special way.

THe other solution would be to create a translation pattern that matches any outbound call and changes the calling # to the desired string before hitting the actual route pattern. You would take all partitions out of this VIPs CSS that could possible hit a route pattern, and then move those paritions to a new CSS that is applied on the translation pattern. so you basically move the privileges from the ip phone/line, to the translation pattern.

The final option would be to apply a Calling Party Transformation CSS on the SIP trunk. THen create a Calling Party Transformation pattern in a partition reachable by the CSS above, this will result in calls routed through the SIP trunk, but with a modified calling party number. Let me know if you have questions

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amigan_99Network EngineerAuthor Commented:
Thanks again Obi Wan!
José MéndezCommented:
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