I do not pick up calls from unknown callers nor numbers I do not know. Let them leave a message. Easier than my blood boiling LOL
Called back however and the number is NOT in service.

it is a scam !

When they called, I was unable to answer as I was on another line.  When I returned their call about two minutes later the teleco intercept stated that "this number is not in service at this time." I have blocked this number in my system and that should be the end of it.  One of the other caller ID companies listed Anthony M Dominic as the owner of this number , however, I waste any more time trying to find the owner.

This number calls but hangs up when I called back they hung up

Caller calls from Arizona and tells me due to a prior repair of my computer, I am now eligible for a free analysis of my computer to determine the status.  Long story short - they will find errors and then offer to "tune up" your computer for some money.  Tune up consists of free programs online - but you have to pay.  Nothing but a scam.  Best to just hang up.