You can have the call go through a translation pattern to change the calling number. For that the CSS assigned to the device and/or directory number cannot have visibility of the partition where you have your directory numbers, it must first “see” the partition where your TP is placed in, then the egress CSS set on the TP must have visibility of the PT(s) where your DNs are.
This is not a straightforward configuration, and it can be difficult for a beginner.
What @Roger Kallberg explained is helpful for someone who is already familiar with CSS partitions and translations. You really need to understand how CSS, partitions, and translations work on CUCM.
