Sen. Tom Udall has proposed a bill that would require cellphone companies to inform customers when they have used 80 percent of their voice minutes, text messages or data use. Under the measure companies would also have to get customer consent before charging for services that exceed customer plans.

Udall (D-N.M.) introduced the Cell Phone Bill Shock Act of 2011 on Tuesday, saying that it would be simple and cost-effective for cell companies to send a text or e-mail to customers nearing their data limit. He said bill shock is becoming more of a problem as companies change the terms of their unlimited data plans or drop them altogether.

“As more and more cellphone companies drop their unlimited data plans, this problem only stands to get worse,” Udall said in a statement. “I am proud to stand up for cellphone consumers and reintroduce this important legislation.”

The senator introduced a similar bill in 2010. In October, the Federal Communications Commission agreed unanimously to issue a proposal for a rule requiring customer warnings about approaching voice, text and data limits and international roaming fees.

In the release, Udall noted that the European Union requires carriers to alert users when they have reached 80 percent of their monthly data roaming services.

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