There could be a scam lurking in your cell phone bill that's ugly yet so preventable.

As more and more Americans disconnect their landlines, criminals have migrated to where the opportunity is (the cell phone industry) and with them has gone the "cram." "Cramming" is the practice where crooks will set up third-party marketing groups that post bogus charges to your monthly bill.

Once the province of monopoly landline companies, the cram is now popping up on cell phone bills, according to The Atlanta Journal Constitution. But here's the secret: The wireless carriers earn a cut of the action from these bogus charges, just as the monopoly landline companies did before them!

One man who was running a cram operation managed to steal $35 million by posting charges on cell phone bills and consumers didn't even notice. That's probably because the hieroglyphics of your bill are almost unintelligible. Cram charges are often disguised with innocuous terms like "special services," "Internet advertising," "service fee," "calling plan" or "minimum monthly usage fee."

A typical cram charge for a business might be $10-$15. For a consumer, it's more like $5-$10.

So what's the alternative to getting ripped off? Either be sure to go through your bill every month page-by-page to vet out any cram charges or better yet, call up your carrier and tell them to block access for third party charges.

However, there is a gray area here with teens on an "add-a-line" plan. Cell providers particularly love these cheap add-a-phone offers for kids that tend to price out around $10 each month. Why? Because the parent must accept responsibility for any charges that are incurred -- even bogus cram charges.