How to Detect SIM Card Cloning

SIM card cloning, a type of fraud, occurs when someone intercepts your SIM card information as you make a call with your cell phone, then copies that information to a different cell phone. The person then makes calls and texts that you are billed for. These cloned phones are difficult for the police to find, so it's important that you pay close attention to your mobile phone bill to ensure there are no unauthorized calls or text messages.

Young man with a mobile phone
Cloning cell phones is a crime.
credit: Photodisc/Photodisc/Getty Images

Step

Open your monthly cell phone bill or access it online.

Step

Check the list of phone numbers the bill shows you called or received calls from. Make a note of any unfamiliar numbers. If there are only a couple of unfamiliar numbers, it's possible they are legitimate -- you may have called a restaurant to make reservations or received a call from your mechanic saying your car was repaired. Call these numbers to confirm they are legitimate.

Step

Check the numbers under you text message section of your bill. Make sure they are all familiar numbers. Call any unfamiliar numbers to ensure they are legitimate.

Step

Make a note of the dates and times of suspicious activity you notice during your normal cellphone use. This activity includes being unable to check voice mail, consistent calls saying they've reached the wrong number or problems placing outgoing calls.

Step

Call your service provider to ask about any suspicious calls or texts listed on your bill or to report other suspicious activity. The fraud department investigates SIM card cloning, but you must change your phone number and existing SIM card to minimize the expenses to your account.

Step

Add a PIN code that must be entered before you can make calls on your cellphone. According to the Better Business Bureau, a PIN code can reduce the chance of your SIM card being cloned by 80 percent.