I updated my iPhone 8 to 15.3.1 per Apple Support yesterday. It did not fix the problem. I then called my carrier who ASSURED me they could fix the issue and had me reset my network on my phone, which cleared network settings, downloaded new settings from AT&T (my carrier) and required me to re-enter my WIFI password, as the entry was removed by the reset. I just now tested this setting by calling a friend of mine, and it STILL shows my number un his phone. I then tried prefixing his number with *67 and called him, and that hid my number as it should. However, the APPLE BUILT IN FEATURE in settings to hide my caller ID does not work reliably. I tested the feature calling several friends and SOME of them could see my number, some could not. It is NOT reliable.