Facebook is prompting users to install its Messenger app, while warning it will be their only option soon. Some users switched to using the Facebook mobile site on their phone browser instead, which still had Facebook’s built-in chat – but now that mobile site work-around has been marked for death, too. The Facebook app for Android and iOS began encouraging people to install Facebook Messenger in August 2014. Facebook is forcing users of its mobile site to install its separate Messenger app if they want use chat, just as it has already done for users of its Android and iOS app.