An FCC Survey  indicated that 30 million Americans—or one in six mobile users—have experienced "bill shock," a sudden and unexpected increase in monthly bills that is not caused by a change in service plans. Bill shock can occur for a number of reasons including unclear or misunderstood advertising, unanticipated roaming or data charges, and other problems.
It can be difficult to know when you're running up a surprisingly high wireless bill, especially if you don't monitor your usage or receive automatic usage alerts.
The FCC's Consumer Task Force recommends these strategies to avoid bill shock today:
- Understand your calling pattern for making voice calls, and ask your carrier for a plan that would be best for your kind of use.
- If you are an infrequent phone user, consider a pre-paid plan. Because you "pre-pay" for all your minutes, these plans make it impossible to go over your set limit.
- Understand what your roaming charges are and where you will incur them.
- Understand your options for data and text plans.
- If you are going to use your mobile phone outside the U.S. for voice, email, and other services, make certain to find out beforehand what charges may apply. (Visit Wireless World Travel  for more information about using a wireless phone in other countries.)
- Ask how your carrier can help you avoid bill shock – with phone or text alerts, by letting you monitor your account online, or by giving you other information.
- If you have tried to resolve a billing issue with your carrier and can not reach an acceptable resolution, complain to the FCC. You can call our Consumer Center, toll-free, at 1-888-CALL FCC (1-888-225-5322), or file a complaint here .
To learn more, read the FCC's White Paper on Bill Shock .
To file comments on the bill shock proceeding, visit ECFS Express .
From the Chairman:
The FCC's Consumer Empowerment Agenda 
Senior Consumers Also Experience Cell Phone Bill Shock 
Bill Shock: Starting to Set the Rules 
Fighting Bill Shock: We Hear You Now 
Denying Bill Shock by Distorting the Facts 
Consumer View: Stop the Shock 
Carrier Compliance: Helping Consumers Avoid Bill Shock 
Tips for Avoiding Bill Shock on your Mobile Phone