You'll soon be able to switch cell phone carriers without losing your number. Verizon Wireless has lost a court challenge that sought to overturn a federal rule requiring companies to let users keep the same phone numbers when they switch carriers.

An appeals court in Washington upheld the Federal Communications Commission regulation, which takes effect Nov. 24. Some members of Congress, under heavy lobbying by the cell-phone industry, have said they may seek to postpone the rule.

Mobile-phone companies say the so-called number portability rule will cost the industry $1 billion to upgrade their networks, plus $500 million a year. They say the fact that millions of customers switch carriers each month without number potability proves it isn't needed.

At an April hearing, judges on the appeals court were skeptical and said they doubted claims that the phone number rule isn't necessary to protect consumers.

"The simple truth is that having to change phone numbers presents a barrier to switching carriers, even if not a total barrier, since consumers cannot compare and choose between various service plans and options as efficiently," Judge Harry Edwards wrote for the three-judge panel of the U.S. Court of Appeals for the District of Columbia.

The Federal Communications enacted a rule requiring number portability in 1996. Verizon Wireless and the cell phone's trade association -- the Cellular Telecommunications and Internet Association -- challenged the rule in court.

Association President Tom Wheeler said his group is disappointed by the decision and said the FCC will now have to define "basic how-tos" involving number portability.

Verizon said it will not appeal the court's decision but called it "bad public policy" and said the rule will divert resources from improving network quality, customer service and developing new products.

There are about 146 million U.S. mobile phone users, or about half the population. At the six largest U.S. cellular operators, an average 2.5 percent of customers disconnect their service each month, which amounts to several million people.