Tellabs Inc. (Nasdaq: TLAB; Frankfurt: BTLA) filed a patent infringement lawsuit against Fujitsu Ltd. (Tokyo: 6702; London: FUJ; OTC: FJTSY) yesterday in the U.S. District Court for the Northern District of Illinois. Tellabs is seeking unspecified monetary damages along with an injunction preventing Fujitsu from future use of the patents. (See Tellabs Sues Fujitsu.)

Tellabs alleges that Fujitsu is infringing on its patents within its ROADM systems and in its FLASHWAVE product line. The patent in question is No. 7369772 and covers methods by which optical line terminals (OLTs) can interact with metro WDM equipment.

But wait a second, didn’t we write a similar-sounding story back in January? With the company names in the headline reversed? It’s true, we did! (See Fujitsu Sues Tellabs .) Tellabs has now launched a suit claiming that Fujitsu that has been infringing one of its WDM patents, following a similar suit launched by Fujitsu in January. The patents in question, however, are not the same.

The patent in this new Tellabs suit is, in fact, different and much newer than those that Fujitsu originally filed suit against Tellabs for in January. It was registered on May 6, 2008.

Tellabs points out, however, that the patent was originally applied for in 2003. "Tellabs has been working on WDM for more than a decade and has invested more than $3 billion in that research and development," a company spokesperson says.

The Fujitsu lawsuit from January is a completely separate case from this new suit. The Tellabs spokesperson said the company is still fighting that lawsuit separately in court and believes the company is “in the clear, but will continue defending itself vigorously.”

Fujitsu could not immediately be reached for comment.

— Raymond McConville, Reporter, Light Reading