Microsoft this week accused mobile ringtone and entertainment firm Funmobile for resorting to spamming Windows Live Messenger users to hawk its wares.

In a lawsuit filed in the Washington State superior court for King County against Funmobile, which sometimes does business as Mobilefunster, Microsoft accused company officials of misusing Microsoft's Windows Live Messenger infrastructure in violation of the terms of service, and said they caused damage by using it to send spam messages.

"Such instant messaging spam, or 'spim,' can take the fun -- and utility -- out of instant messaging," Tim Cranton, Microsoft's associate general counsel for Internet safety enforcement, wrote yesterday on his blog.

He added that so-called "spim" is dangerous.

"Cybercriminals know that for many Internet users, the threat of spim is not yet widely understood," he said. "Spim is more than just an annoyance. It's a serious threat to online privacy and security. Spim campaigns that employ phishing tactics to get your account information can put all the personal information associated with your account at risk."

Funmobile did not return requests for comment by press time.

The lawsuit marks the latest episode in which Funmobile has found itself in hot water.

The company is facing a number of lawsuits relating to its billing practices, with customers claiming that it wrongly slapped them with unauthorized charges for mobile phone content. At least three lawsuits are in appeal, while a fourth is pending.

Additionally, a number of users have registered complaints against Funmobile billing practices on ClassActionConnect.com, a site set up by law firm KamberEdelson to coordinate class-action efforts. Complaints against Funmobile billing practices on the site date back to 2007.

Across the nation, from San Francisco to Boston, the Better Business Bureau gave the company an "F" for failing to solve customer issues including complaints about bait-and-switch advertising, unsubstantiated billing, and unauthorized services.

To obtain IM accounts, Microsoft's complaint alleges that Funmobile used shady practices to dupe users into thinking a friend recommended their products.

"The Defendants collect and store the user's Windows Live ID login credentials. They then utilize those login credentials to access Microsoft's proprietary systems and to access the user's account," the complaint said. "Defendants then 'scrape' or 'harvest' all of the contacts within the user's account, and send unsolicited bulk IMs to each of the user's contacts. As described above, those IMs erroneously purport to be from the user when, in fact, they are simply more misleading commercial solicitations promoting Defendants' Web sites."

"This kind of activity isn't just a violation of our terms of service for Windows Live, it's a violation of our customers' privacy," Cranton wrote.

Microsoft's Windows Live team added that the claims of Funmobile's spim attacks don't mean that the company doesn't work hard to protect its IM users.

"Windows Live takes privacy and security threats very seriously, employing a variety of ever-improving technical, educational and legal means to help keep customers and their data safe," team members said in a blog post.

"That said, malicious attacks are always a risk, as hackers use increasingly sophisticated tools to circumvent security measures," they added. "And while we believe Windows Live is great platform for developers to build companion services on, we do not endorse services purporting to integrate with Windows Live unless they are built by Microsoft or by developers using official Windows Live APIs available at http://dev.live.com."