SAN FRANCISCO -- A federal appeals court in San Francisco has ruled that a lawsuit against AT&T can proceed as a class-action case.

A panel of three judges made the decision Saturday based on a Cingular wireless contract that they said violates California law.

The suit alleges that cell phone customers received inferior service after AT&T's wireless division was sold to Cingular wireless.

Consumer Bob said the cell phone company got away with it because it's often included in the fine print in the contracts that most people sign without ever reading.

And even customers who do read through it still may not understand what they're agreeing to.

When Chris McCann switched cell phone companies, he thought he was free from his original contract. But then he and his wife were hit with a $200 early termination fee because, he later discovered, his two-year contract had been quietly extended an extra year.

"We had no paperwork. We had no signatures. We had nothing from them indicating we had ever done anything to extend our contract beyond the original two-year obligation that we had," McCann said.

"It might not seem right, but it is how they do business," Consumer Bob explained. "Cell phone companies can extend your contract without you ever signing anything."

"Say you call up your cell phone company and you ask for more minutes or just an address to mail a check. You might find your contract has just been extended another two years," Consumer Bob added. "The key to changing providers without paying an early termination fee is knowing when your contract is up. But that's easier said then done -- especially when contracts are extended without your knowledge."

"They never send you anything in writing. It never appears on your bill. You really have no way of knowing unless you call them and specifically ask. And even if you do ask, they seem to be a bit evasive in trying to answer the question," McCann said.

Do you want to avoid this kind of surprise? End every call or visit with your cell phone company by saying clearly you do not authorize any contract extensions.