A federal court is standing up for the right of cell phone users to keep their phone number when they change providers.
The U.S. Court of Appeals for the District of Columbia rejected an appeal by wireless companies.
The companies said the federal "number portability" requirement will be too expensive and compliance by the November 24 deadline will be confusing.
Consumer advocates say the inability to retain numbers is one of the biggest barriers to switching providers for better service and prices.
The three-judge panel said it was reasonable for the Federal Communications Commission to create a regulation that would give dissatisfied consumers more freedom to change carriers.