TIME’s Nahid Siamdoust explains what it has been like:
Like other journalists who work for foreign media organizations, I was banned early on from reporting on the protests against the official victory of Mahmoud Ahmadinejad. First, the Ministry of Culture and Islamic Guidance sent a fax prohibiting me from reporting on the streets. Then I got a call to return my already annulled press card in person. Next, I received an anonymous phone call from a person with a strangely friendly voice, telling me, “There are powerful forces out there that do not want you to continue your work.”
By the end of last week, I was cut off from most forms of communication altogether: mobile phone text messaging had already been blocked on the day of the elections, and as the week went on, the entire mobile network was cut off from about late afternoon until midnight, the time when most demonstrations were being staged, making information-gathering from would-be participants impossible. Later, Internet connections were reduced to snail speed, and satellite television was almost entirely jammed. It was becoming impossible to report on events. The only “news” left unblocked was that propagated by State television. [READ THE WHOLE STORY HERE.]
Also, see this.