The patent encompasses a feature that's not only on Microsoft's IM products but also on those of its rivals America Online and Yahoo. The patent was granted on Tuesday.
Patent No. 6,631,412 could serve as a weapon in Microsoft's battle for IM market share. Microsoft is investing heavily in IM as a springboard for selling communication software to businesses. Later this year,, a software product that will initially offer IM for the enterprise and then expand into Internet voice calling and video services.
The software giant currently offers MSN Messenger as a free download off the Web, as well as Windows Messenger, the IM client for its XP operating system. Both services have amassed millions of users.
Having a patent can be a powerful tool, but only if it can be proven in a court that its owner has bulletproof claims to the invention, according to legal experts. Companies that challenge a patent have to prove the patent owner was not the first one on record for the invention.
"This means that if someone tries to invalidate the Microsoft patent, they would try to find examples of instant messaging that predated the filing date," said Carl Oppedahl, an intellectual property attorney at Oppedahl, Larson & Frisco in Colorado.
A Microsoft representative declined to comment on the patent. Both AOL and Yahoo representatives declined comment as well.
Microsoft is not the first company to pursue a patent over IM. In December 2002,that claimed rights as the inventor of IM. AOL has not flexed its muscle on the patent, and competitive IM services remain active.
The rush to patent elements of IM underscores the application's popularity and potential. IM has become widely used by millions of Web users who exchange text messages with each other in real time. Some of the most popular IM services--AOL Instant Messenger, Yahoo Messenger and MSN--have added features, such as video conferencing, animated emoticons and mobile access.