Strip leading 91 from calling party ANI on call transfers

[Iyad Musleh]

I have CUCM 11.5.1 setup to prepend 91 on all inbound PSTN calls to facilitate seamless callbacks.  I have a 3rd party contact center application connected to CUCM via SIP trunk.  When contact center agents receive a call and subsequently transfer that call back out to PSTN, the 91 is included in the ANI of the outbound call.  Without making any changes on the 3rd party application side, is there any way in CUCM to strip the leading from 91 from the calling party ANI of transferred calls? I thought there might be something on the SIP trunk's "Outbound Calls" settings that can accomplish this, but it's not obvious.  Does anyone have any experience with this or know what needs to be done?

[Roger Kallberg · Accepted solution]

You can use calling party transformation in CUCM tied to the SIP trunk to achieve this.

[Iyad Musleh]

So first, I create a Calling Party Transformation Pattern where the pattern definition is \91.! and the Discard Digits field has PreDot. (I assume this would match any calling number that starts with 91 and removes it, allowing the remaining 10 digits to pass) Then, in the Trunk Configuration page, under the Outbound Calls section, I'd uncheck "Use Device Pool Calling Party Transformation CSS" and from "Calling Party Selection" drop down, select the CSS that includes the partition where the transformation pattern resides. Does that sound about right?

[Nithin Eluvathingal]

That should work.

[Roger Kallberg]

Yes that looks correct. Please note that it’s very important that you don’t mix transformations with normal call routing as that would have unwanted effects. Best is to use entirely own partition(s) and calling search space(s) for this.

[Iyad Musleh]

This worked! Thanks for the pointers.