The secure messaging app is no longer accessible in China, according to multiple reports by users in the country who said they could only use the app via VPN, or virtual private network, as of March 15.
Beijing has not made any announcement about Signal, but it is standard practice for Chinese authorities to block foreign platforms without discussing the move or explaining their reasoning for doing so.
If Signal's outage is the result of a block, the California-based platform would be the latest foreign app to fall victim to the so-called Great Firewall of Censorship. Clubhouse was blocked in mainland China in early February just days after it caught fire with an elite subset of Chinese users. In that case as well, Beijing made no announcement, and Clubhouse users were left to discover the ban for themselves.=
"It may seem surprising that the app hasn't been blocked until now," Charlie Smith, the pseudonymous founder of GreatFire.org, which tracks Chinese online censorship, told Protocol. "One reason might be that the app did not reach the 'threshold' of popularity that the authorities have set for censorship. Another reason might be that the Signal website doesn't have a Chinese language version."
This bulletin has been updated with a quote from Charlie Smith.