If I do not recognize an incoming call, I stop it & let it go to message bank (with an invitation from message bank to leave a message). If it is a genuine call, a message will be left. Saves a lot of time & angst.
When old Fred walked into the common room at the nursing home one morning, Maude said "Fred, your fly is undone", I wouldn't worry about that said Fred, a dead bird never falls out of the nest.