Da generally-mandated/accepted procedure for using da phone in a particular locale.
Da protocall in most jurisdictions is usually fairly simple, straightforward, and obvious --- basically, (1) ask permission before using a phone dat is not yours (like if you're at a friend's house or place of business), (2) "keep it down" during phone conversations, particularly if there are others present in da general vicinity, (3) don't "tie up da lines" for longer than necessary, (4) only use said phone for fairly-necessary and/or of-time-value calls; save non-important and non-urgent calls for when you can use your own phone, and (5) be sure to offer to pay for any toll-calls dat you make on someone else's line.
protocall, a word to describe someone that made a grammar error
its protocall