When I make a call I get a greyed out wave icon on the upper left corner of the screen:
What is it for?
It is the call recording functionality.
Record and transcribe a call on iPhone - iPhone User Guide
It’s grayed out in regions where the function is not enabled.
Note: Call recording is not currently available in the European Union, Azerbaijan, Bahrain, Egypt, Iran, Iraq, Jordan, Kuwait, Morocco, Nigeria, Oman, Pakistan, Qatar, Russia, Saudi Arabia, South Africa, Turkey, United Arab Emirates, and Yemen.