BellSouth filed suit Wednesday against Glenayre Technologies and Call Sciences, Inc., saying the companies had infringed on a patented call routing technology called “one number service.”

BellSouth, which won the patent in 1998, said the suit is the first filed by the company. And BellSouth’s Intellectual Property Marketing Corp. promised an aggressive defense of BellSouth technology.

“Our intention in filing this lawsuit is to vigorously protect BellSouth’s intellectual property,” said Scott Frank, president of the IP marketing group.

BellSouth was awarded 64 patents in 2002 alone. The telecommunications firm has won patents in wireline, wireless, Internet, billing and entertainment sectors.