CHICAGO (CBS) — Crooks are out to steal your cell phone numbers.

Their goal is to get at your bank accounts and other financial information.

As 2 Investigator Pam Zekman found out, crooks are now stealing your phone number in order to drain your accounts.

“I got a text from my wife ‘did you buy a car on Zelle last night for $2,000?’ I’m like not me and we knew something was wrong,” said Bill Stillwaugh.

Stillwaugh also noticed that his phone wasn’t working and eventually learned…

“What happened was my phone number got stolen,”  Stillwaugh said.

It’s called phone porting.

A crook uses your stolen, personal information to transfer your cell phone number to a new phone which they possess.

“They have stolen my cellphone number and technically they are me, because that’s what we use to prove our identity these days, our cell phone,”  said Stillwaugh.

Once the crooks have your number on their cellphone, the crooks assume your identity.

And have the bank send a new password that gives them access to your accounts.

The verification code the bank sends goes directly to the scammer.

In Stillwaugh’s case the crooks were able to withdraw $4,000 from his bank account.

He said he never imagined having problems with his long-time cell phone number.

“It was horrifying,”  Stillwaugh added.  “We were shocked and our first thought was if this just happened, what else could they be doing.”

“Scammers can essentially rob you or rob your bank account without ever actually having to step foot inside the bank branch to do that,”  said John Breyault of the National Consumers League.

“We think this is a very significant problem. We’ve seen warnings about this from some of the nation’s largest wireless carriers who have millions of subscribers,”  said Breyault.

To avoid the phone porting scam experts say you should:

*Attach a pin number to your cell phone account.

*Choose strong passwords and change them frequently.

*Act quickly once you notice fraud to stop money withdrawals.

Lessons Stillwaugh has learned.

“My wife and I both started to look at how we secure our information and how we use passwords.”

The Stillwaughs were able to stop payment and have the $4,000 returned to their accounts.

It’s unclear how or when their personal information was stolen.