Mobile-phone customers may be able to switch to new providers and keep their phone numbers, the U.S. Court of Appeals for the District of Columbia ruled Friday and upheld an earlier decision by the Federal Communications Commission. The court’s three-judge panel said the rule was needed because companies would not likely offer the option on their own.

“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,” the judges said in their opinion.

Tom Wheeler, president of the Cellular Telecommunications and Internet Association, said he was disappointed with the decision.

“The basic how-to’s have yet to be addressed,” said Wheeler in a statement. “If there is to be number portability in November, the FCC must announce final rules by Labor Day or consumers will find chaos in the market.”

The wireless industry estimates that offering number portability would cost them more than $1 billion to implement.

(via Reuters)