In the crackdown following the disputed Iranian presidential election results this weekend, the authorities shut down text messaging, blocked Facebook and YouTube and cut off the BBC Persian-language service — but they forgot about Twitter.
Because of that, the simple microblogging service has become Iran's lifeline to the outside, a way for Iranians to tell the world what's happening on the streets of Tehran in real time — and a vital means of communication among themselves.
Iranian Twitterers, many writing in English, posted photos of huge demonstrations and bloodied protesters throughout the weekend, detailing crackdowns on students at Tehran University and giving out proxy Web addresses that let users bypass the Islamic Republic's censors.
By Monday evening, it had become such a movement that Twitter postponed maintenance scheduled for the wee hours of the morning, California time — midday Tuesday in Iran.
"Our network partners at NTT America recognize the role Twitter is currently playing as an important communication tool in Iran," wrote Twitter co-founder Biz Stone in a blog posting.
"Tonight's planned maintenance has been rescheduled to tomorrow between 2-3p PST (1:30a in Iran)," he added.
Dozens of posts were coming in every second on the Web page http://search.twitter.com/search?q=%23iranelection Monday morning, with and a slower stream at http://search.twitter.com/search?q=%23iranrevolution.
Most of them had to do with a huge rally in central Tehran featuring Mir Hossein Moussavi, the challenger to President Mahmoud Ahmadinejad.
The government announced Ahmadinejad had won with a huge majority just hours after the polls closed Friday evening, despite opinion polls showing Moussavi with a strong lead.
"Khatami has just called for the election to be declared VOID at todays protests in Tehran," tweeted user "moussavi1388" at 10:07 a.m. EDT, referring to the reformist president who preceded Ahmadinejad.
"My people are saying perhaps a million on the streets of Tehran now," wrote "persiankiwi," another Iranian tweeter, at 10:14.
"Mousavi&Karroubi had speeches for hundred thousands ofpeople fromthe roof of a car in Tehran Demonstrationagainst coup d' etat," posted Twitter user "madyar" at the same time.
"Karoubi, Mousavi, Khatami, Karbaschi are among protesters," wrote Iranian programmer "knv."
Mehdi Karroubi is a respected elder cleric and reformer who also ran in the presidential election. Gholamhossein Karbaschi is a former reformist mayor of Tehran who endorsed Karroubi and maintains his own Tweeter account in Farsi at http://twitter.com/gkarbaschi.
"We call on Mr. Karoubi's supporters to participate in the activities he initiates for protecting the votes," read a translated post on Karbaschi's Twitter page, which appeared to be mainly updated by aides.
Another Tweeter, "Change_for_Iran," stopped posting around 7 a.m. EDT because, as he put it, "it's worth taking the risk, we're going. I won't be able to update until I'm back. again thanks for your kind support and wish us luck."
"No foreign leader had congrats to Ahmadinejad but Hemas terrorists and Hugo Chaves dictator," noted Iranian bioengineer Amin Abbaspour.
Even larger was the active reposting of Iranian tweets from people outside the country, doing all they could to spread the word.
"Lotfan," a Iranian tweeing from Toronto, was one of the leaders in the effort, tweeting "Initial Estimates are tallking about 3 Million people" about the Monday-afternoon rally.
"Reaction to Iranian election strong even here in Malaysia," tweeted user "Sombit."
"My wife spoke with relatives in Shiraz: 'They can't arrest 65 million people' was the comment," wrote American "Dereklowe."
User "Guy_Murray," a California lawyer, seemed to be spending most of his morning reposting tweets from Iran.
Even actress Elizabeth Banks, star of "Zacha and Miri Make a Porno," got in on it, tweeting late Sunday evening that "Amazing video coming out of Iran c/o the BBC. S*** appears to be going down."