Cloning occurs when hackers scan the airwaves to obtain SIM card information, electronic serial numbers and mobile identification numbers, and then using that data on other phones.

Cloning can happen anywhere, anytime that you’re using your phone. The bad guy simply uses an interceptor, hardware, and software to make a phone exactly like yours.

A few years ago, I was in San Diego on business. Two weeks later I received a call from my carrier alerting me to $1500.00 worth of international calls I had not made. The activity triggered an alert within their system and they shut my account down.

Fortunately for me, my carrier recognized the fraud and relieved me of the charges, rather than me discovering it and having to fight to reverse the charges. Apparently, it was a known issue that scammers in Tijuana were cloning U.S.-based phones.

Anita Davis, another mobile clone victim, wasn’t so lucky. One month, her cell phone bill showed $3,151 worth of calls in one month, to Pakistan, Israel, Jordan, Africa, and other countries. Anita called her carrier immediately and told them she didn’t know anyone in those countries, or anyone outside the U.S. for that matter. She says, “They told me I had to have directly dialed these numbers from my cell phone and I needed to make a payment arrangement or they would send my bill to collections.” After begging and pleading, Anita convinced them to drop the charges.

The extent of your vulnerability varies depending on your phone and the network you’re on. Cloning mobile phones is becoming increasingly difficult, but consumers can’t do anything to prevent it from happening. The best way to mitigate the damage is to watch your statements closely. The moment you see an uptick in charges, contact your carrier and dispute the calls.

Robert Siciliano, personal security expert contributor to Just Ask Gemalto, discusses mobile phone spyware on Good Morning America. (Disclosures)