Mr. Number is a great way to find out exactly who owns that mysterious number. Whether you get a text or a call from a number which you don’t recognize, Mr. Number only needs a few seconds to tell you exactly who’s behind the number.
When you receive a text or call from a number that is not in your contacts list, Mr. Number immediately searches its database for a matching number, and within a few seconds, a screen appears with the person’s name(John Smith), phone number, and location(Sacramento, CA). This is a totally free service and works 90% of the time. Definitely a great app to download; however, this will not work if you are being called by a blocked or restricted number. In my next edition of “Recommended App”, I’ll introduce you to a great(payed) app which can actually unblock restricted numbers.
Source: http://mrnumber.com and personal experience