Twitter is a medium that has proven vital to activist, who use the site to inform each other of arrests, locations, and any other relevant information, such as where security is highest and whether police are carrying tasers.
While demonstrators scrambled to keep each other in touch by other means, they soon found that their mobile phones were also not working.
The government seems to have scrambled the signals in major downtown areas, including Tahrir Square, where around 40,000 demonstrators gathered on Tuesday night, and Talat Harb Square.
The crackdown is seen as an indication that the government will be increasingly tough on demonstrators hoping to oust 30-year president Hosni Mubarak as Tunisians ousted 23-year president Zine el-Abidine Ben Ali.
By Sallie Pisch
