iPhone clicking sounds on certain calls to commercial numbers

This issue has been floating around since at least 2017 - and no apparent solution - REALLY? It seems to happen when calling only some commericial numbers, such as Southwest Airlines, and numerous others - and it DOES NOT occur to same numbers using for example Skype Out (I don't have other phones to test the issue with).

Has anyone heard of a solution or if not APPLE Y O U need to find out what is going on and fix it.

In case it pertains, my cellular provider is ATT Wireless.