LONDON (Bloomberg) - Motorola Inc. and BlackBerry maker Research In Motion Ltd. sued one another over mobile-phone patents, each claiming their competitor is using handset technology without permission.

Motorola, the biggest US maker of mobile phones, asked a US judge in Marshall, Texas, on February 16 to order Research In Motion to stop the infringement. Research In Motion filed its own suit in federal court in Dallas the same day over similar claims, Research In Motion spokeswoman Tenille Kennedy said yesterday.

Research In Motion has more than eight million subscribers in North America for its BlackBerry e-mail device. Verizon Wireless, AT&T Inc. and other phone companies pay the company a fee of about $6 a month for each subscriber that uses BlackBerry e-mail. The Motorola suit targets Research In Motion's 8100, 8130, 8320, 8800, 8820 and 8830 model devices, as well as BlackBerry Exchange Server software.

Research In Motion "willfully" infringed the patents, causing "irreparable harm," Schaumburg, Illinois-based Motorola said in its complaint. Motorola also is seeking cash compensation for past infringement of the inventions, according to the complaint.

The technology Motorola is suing over includes a method of storing contact information in wireless e-mails and a way of recognizing incoming phone numbers, court papers show.

Research In Motion's lawsuit claims Motorola infringed Research In Motion patents, including one for a device "with a keyboard optimised for use with the thumbs," according to court papers provided by the Waterloo, Ontario-based company. It also accused Motorola of anti-competitive behavior by demanding "exorbitant royalties" for its patents.

The Eastern District of Texas, where Motorola's complaint was filed, was the second-most-favorable jurisdiction for patent owners who sued from 1995 to 2006, according to a PricewaterhouseCoopers LLP study last year. Only the Western District of Wisconsin was found to be more favorable.

Research In Motion in 2006 paid $612.5 million to settle a patent dispute with NTP Inc., ending a four-year legal battle and averting the shutdown of BlackBerry e-mail service across the US NTP claimed its patents covered technology used in BlackBerry devices.