Which of the following are you most likely to do if you find you've missed a phone call? (Assume you're not expecting a call, you don't recognise the number, and the caller hasn't left a message.)
Missing telephone calls
Ring the number.
Ring the number, but only if the missed call is very recent.
Wait and see if they call back. If not, ring the number.
Do nothing. They'll call again if it's important.
Google the number and only call it if I can find out who it belongs to.
Google the number, then call it regardless of whether I can find out who it belongs to.
I do more than one of these and couldn't possibly say which I'd be more likely to do on a given occasion.
I don't know, this never happens to me.
I'd do something else.