Speak to tech support (Score 2, Interesting)

I used to work in the cell phone business, and here is an easy way to have them check for cloning. Speak with technical support, and have them check which towers you are pulling service from when these calls occur. If you make a call at 3:28pm connected to a tower in Los Angeles, and then 15 minutes later it says you are connected to a tower in San Diego; that is proof enough something weird is happening. Just highlight all these questionable calls on your bill, then ask to have the calls just before and jjust after checked to see which towers are in use.