Search giant Google, Inc. confirmed Monday morning that its Gmail, YouTube and encrypted search services have been unavailable to Iranians since Feb. 10, the day that rumors began to circulate that the whole country had been taken offline.

Shortly after Google's confirmation Monday morning, The Associated Press began receiving reports that access to email services had returned after a four-day outage, and the Iranian government said it wasn't responsible.

Previously working countermeasures against Iranian censorship, however -- like the use of virtual private networks and proxies -- were shut down on Thursday, leading some to theorize that state-run Internet service providers (ISPs) have since began targeting the world's most popular websites with blockades.

The blackout and a year-long house arrest of opposition leaders has drawn calls for another round of mass protests starting Tuesday, Feb. 14, and government security forces are reportedly already gearing up to meet the demonstrators head-on.

The parliamentary elections are also coming up on March 2. The last national election in 2009 resulted in mass chaos after Mirhossein Mousavi and Mehdi Karoubi, the leading reformers, said the vote had been rigged. Reformers have said they are boycotting the 2012 vote. Saturday also marked the 33rd anniversary of Iran's revolution that overthrew a U.S.-sponsored dictator and installed a brutal theocracy in its place -- a politically sensitive time for Iran's conservative hardliners who've been in power ever since.

The last time a nation's government cut its whole population off from the Internet, revolution was afoot: In Libya, once the Internet vanished, the insurgency picked up pace with an urgency. So too was the case when Egyptian ISPs stopped working and mobile phones were cut off in late January, 2011, marking the start of the real protests after weeks of simmering public anger.

Once the Internet turned off in Egypt, people flooded into the streets and toppled the regime within days. It took a bit longer for Gaddafi's Libya, but the result was nearly the same.

Iran's digital censorship apparatus was built by Siemens AG and Nokia Corp., which sold the country the ability to intercept or block communications on a large or narrow scale.

The technology provided by Western corporations even allows the regime to intercept opposition communications and alter them, inserting disinformation into potentially crucial electronic messages.