RICHMOND, Va. — NTP Inc., the patent-owning entity that got $612 million out of a suit against BlackBerry maker Research in Motion Ltd., has hit the nation's top four wireless carriers with similar lawsuits.

The cases, filed last Friday in the federal district court in Richmond, contend that the carriers infringe on eight patents related to wireless e-mail that were granted between 1995 and 2001 to Thomas Campana, whose inventions became NTP's portfolio. The defendants are AT&T Inc., Deutsche Telekom AG's T-Mobile USA, Sprint Nextel Corp. and Verizon Wireless, a joint venture of Verizon Communications Inc. and Vodafone Group PLC.

Five of the eight patents were also at issue in the RIM case.

Verizon Wireless, T-Mobile and AT&T declined to comment. A Sprint Nextel spokeswoman did not return a message yesterday.

With Campana now dead, NTP is now run by his attorney, Donald Stout. Stout declined to comment on the new cases.