Its a fairly standard procedure to maintain law and order, the world over.
Pakistan
Security: Cell phone services in Balochistan suspended on Pakistan Day – The Express Tribune
Mobile phone service suspended in Balochistan
Cellular services to remain suspended in twin cities today
Pakistan suspends mobile phone service in 50 cities
China
Xinjiang Internet Restored after 10 Months - Xinjiang: Far West China Suspended for 10 months!
SMS returns to Xinjiang Switched off 8 months!
SMS services have been suspended in parts of Sichuan province -Reporters sans frontires - China
Turkey
Turkish protesters using encryption software to evade censors | Technology | guardian.co.uk
America
BART Turns Off Mobile Phone Service At Station Because It Doesn't Want Protestors To Communicate
Pakistan
Security: Cell phone services in Balochistan suspended on Pakistan Day – The Express Tribune
Mobile phone service suspended in Balochistan
Cellular services to remain suspended in twin cities today
Pakistan suspends mobile phone service in 50 cities
China
Xinjiang Internet Restored after 10 Months - Xinjiang: Far West China Suspended for 10 months!
SMS returns to Xinjiang Switched off 8 months!
SMS services have been suspended in parts of Sichuan province -Reporters sans frontires - China
Turkey
Turkish protesters using encryption software to evade censors | Technology | guardian.co.uk
America
BART Turns Off Mobile Phone Service At Station Because It Doesn't Want Protestors To Communicate