NTP Inc, which last year won a $612.5 million settlement from the maker of BlackBerry wireless devices, has sued four of the top U.S. mobile service providers for infringing eight patents related to wireless e-mail.

The lawsuits, against Verizon Wireless, Sprint Nextel Corp (S), T-Mobile USA and the mobile unit of AT&T Inc (T) were filed September 7 in the U.S. District Court for the Eastern District of Virginia, according to court documents.

NTP, which is asserting patents related to products, processes and services used for wireless e-mail systems, said it was seeking a jury trial, injunctive relief and monetary damages.

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The suits follow a case NTP brought against Treo mobile phone maker Palm Inc (PALM) in November last year.

The judge in the Palm case granted a stay of the suit in March this year and agreed to strike an NTP complaint alleging misbehavior by Palm at the U.S. Patent and Trademark Office.

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Virginia-based NTP is best known for its prolonged patent infringement battle with Research In Motion Ltd. (RIMM), maker of BlackBerry, the popular wireless e-mail device.

Officials for AT&T and Verizon Wireless, owned by Verizon Communications Inc (VZ) and Vodafone Group Plc (VOD), declined comment. Sprint and T-Mobile USA, owned by Deutsche Telekom AG (DT), were not immediately available.