The Saudi government is lifting a ban on calls made through online apps on Thursday but will monitor and censor them, a government spokesman said.
All online voice and video call services -- like Microsoft's Skype, Facebook's WhatsApp and Messenger, and Rakuten's Viber -- which satisfy regulatory requirements were set to become accessible overnight.
However, on Thursday morning, Messenger and Viber appeared to remain blocked inside the kingdom.
Adel Abu Hameed, spokesman for telecoms regulator CITC, said on Arabiya TV on Wednesday that new regulations were aimed mainly at protecting users' personal information and blocking content that violated the kingdom's laws.
Asked if the apps could be monitored by the authorities or companies, he said: "Under no circumstances can the user use an application for video or voice calling without monitoring and censorship by the Communications and Information Technology Commission, whether the application is global or local."
Saudi Arabia, which introduced blocks to internet communications from 2013, along with its Gulf Arab neighbors have been wary that such services could be used by activists and militants.
Gulf Arab states, except the island kingdom of Bahrain, were mostly spared the "Arab Spring" mass protests often organized over the Internet which roiled much of the region in 2011.