Three of the four largest U.S. wireless phone carriers have agreed to stop billing customers for most third-party charges on mobile phone bills, Iowa's Office of the Attorney General announced yesterday.


AT&T Mobility, Sprint and T-Mobile will stop charging customers for commercial Premium Short Messaging Services, which give users the ability to purchase or subscribe to messaging programs provided by third-party content providers, PCWorld reported.


Those messaging services account for a majority of third-party charges on cellphones, and the majority of complaints of "mobile cramming," which occurs when a company charges mobile phone customers for a service they didn't order.


Iowa Attorney General Tom Miller is part of a group of 45 state attorneys general who have put pressure on wireless companies to stop mobile cramming.


His office said in a news release that Iowa consumers have complained about unauthorized monthly charges ranging from $9.95 to $24.95 per month. The charges have been for services that the customers didn't request or use.


In many cases, consumers had been paying cramming charges for several months without realizing it, and have been unable to get a full refund or even block additional charges.


Cramming is estimated to cost Americans $2 billion a year, according to this article in PCWorld.