A federal judge in Boston on Monday granted an injunction against Boston Communications Group, Inc., which provides customer management solutions for prepaid wireless companies. The injunction says that companies using BCGI’s solutions for their prepaid wireless programs, including Cingular Wireless, must stop accepting new customers and shut down their services within 90 days.

The injunction could ultimately effect more than 3.1 million prepaid subscribers at several wireless carriers.

Cingular Wireless has asked for a stay of the injunction while it files an appeal.

Cingular Wireless spokesman Mark Siegel said the injunction does not apply to the “vast majority” of Cingular’s prepaid wireless customers, who use a different type of network technology. He said Cingular would also seek a stay of the injunction while it appealed the case.

“We intend to continue to provide service to all prepaid customers, including those on the BCG platform,” Siegel said. He declined to say what steps Cingular might take if the injunction is not lifted.

A spokeswoman for BCGI could not immediately say who the other affected carriers were. The company has sold services in the past to a variety of carriers, including Alltel Corp. and Nextel, now a part of Sprint Nextel Corp. — Reuters

At issue are two patents held by Freedom Wireless, which a jury found in May that BCGI had infringed. The court had ruled in September that the two patents were fully enforceable.

“The injunction prohibits any of the defendants from making, using, or selling prepaid wireless services based on the systems found to infringe, either by themselves or jointly with any other companies,” said Bill Price, lead trial lawyer for the plaintiff.

While the defendants are prohibited from adding new customers to the infringing systems, they can continue to serve current customers for 90 days, but they must pay Freedom Wireless a 2.5-cent per minute royalty for each subscriber minute used during the grace period.

The ruling is expected to affect Cingular’s GoPhone prepaid service, Boost Mobile, Alltel’s prepaid service, and other unnamed prepaid services. Verizon Wireless settled with Freedom Wireless earlier this year, and is not affected.