As of this afternoon, "88 percent of Egypt's Internet is effectively not there anymore," Rik Ferguson, a senior adviser at computer security firm Trend Micro, told AOL News.

The only major Internet service provider that's still connected to the outside world is operated by Noor Data Network, which carries traffic for the Egyptian Stock Exchange.

This isn't the first time that a repressive regime has sought to dampen dissent by interfering with the Internet. When Iranians took to the streets following the disputed 2009 elections, authorities tried to deny access to Facebook, Twitter and foreign news sites. But those Net barricades proved largely ineffective as foreign activists provided Iranians with anti-censorship tools such as Tor, a program that cloaks users' identities and allows them to access blocked sites.

Egyptian authorities appear to have learned from Iran's flawed attempt at online censorship. Realizing that targeting individual sites was ineffective, the government opted to carry out an "unprecedented shutdown of all modern communication channels," Brett Solomon, executive director of Web freedom group AccessNow.org, told AOL News.

So how did Mubarak and Co. kill the Internet? The fact that Noor Data Network is still up and running suggests the regime hasn't cut or unplugged the data cables that link Egypt to the rest of the world. (That's what Myanmar's military junta did in 2007, when it wanted to stop news of its murderous crackdown on protests led by Buddhist monks from leaking out).

Instead, Ferguson says it's likely that someone in the government simply called up each of the country's 10 or so ISPs and told them to turn off their service. Engineers at each provider would then change the way their traffic flows in and out of Egypt, and any cafes, schools, embassies or homes that relied on those ISPs would suddenly find themselves living in a Web-less world.

Ferguson adds that this tactic works well in developing countries like Egypt where there are relatively few ISPs.

"But it'd very difficult to do this kind of thing in any well-developed Internet economy, such as the U.K. or U.S.," he said. "We have far more service providers, so you'd need the cooperation of hundreds or possibly thousands of people."

Such an act of Net censorship might be almost impossible in the West, but Web activist Solomon notes that Western companies have played a key part in Egypt's communications breakdown. Local cell phone operators Vodafone Egypt (which is 55 percent owned by British telecom giant Vodafone) and Mobinil (71 percent owned by France Telecom) both obeyed a government demand and suspended their service in parts of Egypt today.

Vodafone said in a statement that "under Egyptian legislation, the authorities have the right to issue such an order and we are obliged to comply with it." France Telecom said, "The Egyptian authorities have taken technical measures which prevent Mobinil from serving its customers. We apologize to our customers for this."

Solomon argues it is "outrageous" for these companies to claim that they are simply complying with Egyptian law.

"This is clearly in contravention of all international standards and the standards of their home countries, such as the freedoms of expression and association guaranteed under the European Convention of Human Rights," he said.

Mubarak's phone and Internet clampdown will clearly hamper Egyptian activists' ability to organize and spread their message. But Ferguson says this authoritarian move highlights the need for protest movements to use more than one method of communication.

"We extol the virtues of the Internet and new media, saying they make it easier for people in repressive regimes to access information more freely," he said. "But if that regime has control over the Internet, then maybe we're relying on the Web at the expense of more traditional and resilient forms of offline communication."

Protesters are already starting to turn to older, less centralized communication systems. Some activists reportedly are sending messages over shortwave radio, while others are distributing photocopied pamphletsexplaining what gear protesters need to bring to demonstrations. Necessary items include goggles -- to protect eyes from tear gas -- and cans of spray paint, which can be used on police officers' visors.

Egypt's Internet may be dead, but its uprising is still very much alive.