The Signal Messenger app is displayed on a smartphone in Hong Kong, China.
Roy Liu | Bloomberg | Getty Images
GUANGZHOU, China – The Signal encrypted messaging app has stopped working in China and is now only available through a virtual private network (VPN).
China blocks many foreign apps and services including those from Facebook and Google. But before that Signal was not banned by the name Great Firewall.
Tokens say they are rotated to the end, meaning that the company itself or outsiders can view the content of messages between a sender and the intended recipient. This also means that authorities cannot snoop on messages.
CNBC did not test Signal on three different devices and messages that did not go through, suggesting that it was blocked by authorities. The app was still available for download through the Apple App China Store.
No tokens were immediately available for comment when contacted by CNBC.
The messaging app, however, still worked when used with a VPN. A private or virtual VPN network allows users to protect privacy and overcome internet restrictions by connecting to servers around the world.
Blocked signals in China reflect the growing internet censorship in the world’s second-largest economy.
Signal was downloaded earlier in the year after rival WhatsApp changed its terms of service to allow the sharing of some data with its parent company Facebook.
The brand is relatively small in China with 510,000 downloads so far from Apple’s App Store, according to Sensor Tower. But the app provided a rare way to send encrypted messages through a foreign platform without a VPN.
However, China’s largest messaging app is still WeChat owned by Tencent with over a billion users.