Do I need call tracking?

Yes, if so many calls come in that the floor cannot note where they came from. You do not need a different number if you are a small venue and the question at the door already fits on a piece of paper. Count a week’s calls and how many had no source. If there are few and you ask, the paper is enough. A divert is installed and the customer calls a number that is not the one on the door. The listing and the ad state different phones. Either the floor sheet, or a tracking number that forwards to the real one and does not replace the one on the listing. You pick one and write it in the note.