The Texas cable industry filed suit Thursday in a last-ditch effort to block a new state law that will make it easier for big telephone companies to start selling television services.

The lawsuit targets Senate Bill 5, which allows SBC Communications Inc. and Verizon Communications Inc. to launch their Internet-based television services without having to negotiate scores of local franchise agreements.

Instead, they can get a single statewide franchise, which will save them time and money as they enter a new business that could mean billions of dollars in new revenue.

Gov. Rick Perry signed the measure into law Wednesday. The phone companies already had planned to launch pilots of their new services later this year.

The Texas Cable & Telecommunications Association maintains that the law gives the phone companies an unfair advantage, leaving cable companies burdened by the terms of local franchise agreements until they expire, which in some cases is years from now.