Sharon police said local police departments have been warned about a scam in which someone calls an unsuspecting person and says they are testing mobile phone circuits. The caller asks the person to dial a series of numbers to conduct the test, police said.

If the sequence of numbers is dialed, the scam artist can access the phone's "subscriber identification module card" which allows the scam artist to make calls at the victim's expense, police said.

Anyone who receives such a call should hang up immediately -- without dialing any numbers -- and record the date, time, any caller identification information available and any other information that may be helpful to police. They should then call either local or state police and report the call, police said.