While it may be tempting to call a phone number back, we don't advise returning their call if you don't know who is calling you. Scammers are always looking for ways to exploit unsuspecting people. For example, some robocalls occur to see if your phone number works. Other times, a caller wants to charge you for the phone call (i.e., an international call). Therefore, it isn't a good idea to call the number back.