Another solution is a reverse phone look up.  Let’s say that you keep getting the same phone number calling your home while you aren’t there and you think it may be someone that you know.  You can use these services, which are often provided on the web, to help look up phone number and find out who it belongs to.  Here, you can often get some additional information such as the name and current address of the person who is registered to the phone, connection status as well as information regarding their phone company.  This is a great tool when the person calling is prank calling you or harassing you.