Accused of being home to online scammers, San Francisco Internet service provider Intercage has been unplugged from the Internet ... for the second time this week.

Intercage, which has also done business under the name Atrivo, was first knocked offline on Saturday when its last upstream partner, Pacific Internet Exchange, terminated service. A few days later, another service provider called UnitedLayer agreed to provide it with service, giving it a lifeline to the Internet.

Intercage has been heavily criticized by the Internet community for tolerating online scammers. Last month, security researchers published a damming white paper on the ISP, describing it as a "major hub of cyber crime." The researchers found that 78 percent of the domains and mail servers on Intercage's network were hostile.

Complaints about malicious Web sites and spam servers on Intercage's network went unacknowledged for years, researchers say.

In recent weeks, Intercage executives had argued that they were making a good-faith effort to cut down on cybercrime, but it all may have come too late.

After being notified of more problems on the network this week, UnitedLayer pulled the plug on Intercage late Thursday afternoon, said UnitedLayer Chief Operating Officer Richard Donaldson. "We decided that, given the stuff that was going on and with a couple of infractions that we were made aware of, that they needed to purge themselves of any [malicious] stuff that remained," he said.

Even though UnitedLayer had been peering with Intercage and providing it with Internet connectivity since Monday, computers on the Intercage network were largely out of reach to most Internet users. That's because UnitedLayer's own upstream provider, Global Crossing, had been blocking traffic from Intercage's address space, Donaldson said.

Intercage President Emil Kacperski could not be reached for comment Friday.

But according to Donaldson, Kacperski is evaluating whether his company can continue as a business. "I honestly don't know if they're going to be around for much longer," he said.

The IDG News Service is a Network World affiliate.