Dec. 14 (Bloomberg) -- Nortel Networks Corp., North America's biggest maker of telecommunications equipment, claimed Vonage Holdings Corp. is infringing 12 patents covering technology used in managing telephone data.

Vonage, the money-losing Internet phone company, sued Nortel's U.S. unit in August seeking to invalidate three of the patents. Holmdel, New Jersey-based Vonage said the patents shouldn't have been issued by the U.S. Patent and Trademark Office.

Nortel, based in Toronto, denied the allegations in papers filed today in federal court in Wilmington, Delaware. It claimed in the filing that Vonage is violating the three patents and nine others.

``Defending our intellectual property rights is a top priority for Nortel,'' said Nortel spokesman Mohammed Nakhooda. ``That's why we are seeking damages and to put an injunction on the use of our technology with respect to Vonage.''

An injunction would prevent Vonage from using technology that relates to 911 and 411 calls, as well as its ``click to call'' feature, Nakhooda said.

``The litigation is ongoing and both parties have filed and will continue to file papers,'' said Vonage spokesman Charles Sahner. Nortel's filing ``is a countersuit in defense.''

Vonage fell 3 cents to $2.05 at 4 p.m. in New York Stock Exchange composite trading. Nortel declined 9 cents to $16.08.

The Delaware case is Vonage Holdings Corp. v. Nortel Networks Inc., 07CV507, U.S. District Court, Delaware (Wilmington).

To contact the reporters on this story: Jeff St.Onge in Washington at jstonge@bloomberg.net; Amy Thomson in New York at athomson6@bloomberg.net

Last Updated: December 14, 2007 18:21 EST