It's called cramming, and it happens when unauthorized charges are put on your phone bill.
The Federal Communications Commission just approved new rules to combat this fraud, but consumer groups say the commission didn't do nearly enough.
On Friday, the FCC approved new rules that will require landline telephone companies to tell customers - at the point of sale, on their websites and on each bill - how to block unauthorized third-party charges if the company offers that option. They're not required to offer a blocking service.
Landline carriers that bill for non-telecommunications services from third parties will be required to place those charges in a separate section of the bill to make them easier to find and review.
Consumer groups are disappointed the FCC did not do more to stop crammers. They had ashed the commission to prohibit phone companies from putting charges for other companies on their phone bills unless the customer agreed to this service.
The FCC did not do that. Commissioners say they will "consider" whether more anti-cramming rules are required.
Consumer groups had also asked that all anti-cramming rules apply to cell phone and voice-over Internet phone services, as well as landlines.
The commission did not do that. Instead, the commissioners said they would "monitor" complaints. I should point out that right now, a third of all cramming complaints are from wireless customers.
So how do you protect yourself? Check your phone bills - all of your phone bills - every month for mysterious charges that could be bogus. You need to do this even if you get your bill online and use auto-pay.
Crammers are sneaky. A common trick is to put small charges - $10 or less - onto the bill, hoping you won't notice. Over time, this can really add up.
More information about cramming is available online.