AS unrest in Syria erupted into public demonstrations and a bloody crackdown that has claimed over 6,000 lives in the last year, the regime of Bashar Assad sought to neutralise one of the most potent tools in the protesters’ arsenal: text messages sent via mobile phones.

The Syrian government has ordered blocks on text messages when they contain politically sensitive terms such as “revolution” or “demonstration,” according to two people familiar with the filtering systems. A unit of the Syrian intelligence apparatus, known as “Branch 225,” often issues the instructions on which messages to block, they say.

Syriatel Mobile Telecom, the country’s largest mobile- phone operator, conducts the blocking with equipment from Cellusys, a privately-held company based in Dublin, according to one of the people, who is familiar with the filtering.

Cellusys delivered a filtering system to Syriatel in 2008 as the mobile operator struggled to combat viruses and spam, which can be blocked by such gear, according to Cellusys Chief Executive Officer Dawood Ghalaieny. Syriatel is controlled by Rami Makhluf, cousin of President Assad, according to the Department of the Treasury, which enacted sanctions against the company last year.

In addition, another Irish company, AdaptiveMobile Security, which is also based in Dublin, has supplied message- filtering technology to MTN Syria, the country’s second-largest mobile operator, according to four people familiar with that system.While AdaptiveMobile executives declined to comment for this story, in interviews last year concerning the sale of its product to a mobile operator in Iran, they said its technology is for blocking spam, viruses and inappropriate content, not political repression.

The sales by Cellusys and AdaptiveMobile were legal. The European Union tightened restrictions last year on sales of equipment to Syria that can be used for internal repression, however it’s unclear whether the gear is prohibited by the new rules.

The filtering of text messages has curbed the protesters’ ability to use technologies that helped organise and fuel dissent in other countries across the Middle East and topple autocratic regimes in Tunisia, Egypt and Libya, according to political opposition groups.

”When the government shuts off those modes of communications, the opposition is that much more constrained,” says Rafif Jouejati, a McLean, Va.-based spokeswoman for the Local Coordination Committees, an umbrella organisation of Syrian groups that are staging protests.

Cellusys says it hasn’t sent workers to the country since 2009 and isn’t sure how its technology is being used today.

“Once they have the systems, they control it,” says Ghalaieny. “If it is used for something else, there is not much that can be done.”

In response to questions sent by email, AdaptiveMobile CEO Brian Collins replied in writing that Bloomberg’s information was incorrect without providing specifics. AdaptiveMobile executives did not respond to follow-up inquiries.

The Syrian government’s escalating efforts to block opponents’ text messages are illustrated by a list said to document the words and phrases being filtered on Syriatel’s network, obtained by Bloomberg News. The document’s authenticity couldn’t be independently verified, because Syriatel and the Syrian Embassy in the United States didn’t respond to several phone calls and emails. It contains only one reference to Syriatel and doesn’t bear a company logo.

Many of the facts in the document, however, were not publicly known and have been corroborated by Bloomberg News. For instance, the bottom of the document has several notations that indicate a Cellusys technology called SMS Defence is being used to filter the text messages. The company’s sale of its message- filtering technology to Syriatel was confirmed by Cellusys after Bloomberg asked about its inclusion on the document.

The document also indicates that Syria’s intelligence unit, “225,” issued many of the text-message filtering orders, as described by two of the people with knowledge of the filtering.

The document suggests a government trying to stay ahead of burgeoning unrest by adding scores of new political words and phrases, mostly in Arabic.

About half of the 300 filters include the dates they were requested, which range from November 2010 to December 2011. More than two-thirds relate to political unrest, while the rest appear to target spam or viruses.

Nearly half of the filters were requested by “225,” according to the document. It is the same intelligence unit that issues orders to block web sites inside of Syria, according to human rights groups. The unit also issues orders for blocking of some spam and viruses on the mobile network for fear they could be used to disseminate information to Syrians, according to two people familiar with the systems.

The filters are often instructed to block text messages, while sending “positive acknowledgment” to the sender that the message has been delivered, according to the document.

By arrangement with Washington Post