When you place a phone call using YAPI Mobile app or YAPI UH app, YAPI uses your office phone number as a caller id (or any other phone number you want YAPI to use as a caller id). To setup a caller id number, launch YAPI, open Global Configuration, go to CT tab, and enter your Practice number. Click Verify button.  YAPI will give you a numerical code to enter when YAPI  calls your phone, in order to verify that the phone number you gave is correct.

Click Ok button, answer the call, and enter the verification code.