1. Changed your mind? Act fast. With the big four carriers — AT&T Wireless, Sprint Nextel, T-Mobile and Verizon Wireless — you may cancel a contract without penalty within 30 days of signing. Miss the deadline and you face an early-termination fee of up to $200 per line.

2. End your contract and the line could go dead. Most U.S. wireless devices, unless modified, work with only one network. AT&T and T-Mobile "lock" their wireless phones to make them inoperable on any other network, although T-Mobile customers may ask the carrier to unlock their phone. For now, Verizon permits customers to use only approved phones on its wireless network. Sprint will activate a non-Sprint phone if a customer requests it and the phone is compatible with the company's network.

3. A swap meet could be your ticket out. You can transfer your contract to another person as long as that person passes a credit check. At Web sites such as Celltradeusa.com and CellSwapper.com, you can list your provider, how long you have left on your contract, and your phone and its available accessories in hopes that the combination will attract someone looking to "swap in" to a short-term deal without an activation fee. The sites charge about $20 to match you with a person who will assume the remaining portion of your contract.

4. Watch your mail for adjustment notices. Boilerplate notices from your provider are easy to overlook. When your cell-phone carrier changes your contract, however, you may have a couple of weeks to opt out without paying a fee, so read the fine print. But remember that loopholes cut both ways. If you modify your contract, be sure the carrier doesn't extend it because of your changes.

5. Remain a free agent. All the major carriers offer pay-as-you-go services that allow you more flexibility than long-term contracts. The downside? You will likely pay more.

6. The message may be getting through. In 2006, Verizon began reducing its $175 early-termination fee by $5 for each month you complete on your contract. AT&T, Sprint and T-Mobile say they will discount their early-termination fees.

Thomas M. Anderson is an associate editor at Kiplinger's Personal Finance magazine. Send your questions and comments to [email protected].