The apps, for iOS and Android, now allow people to message each other even if they aren’t Facebook friends.
The updated app was available previously in a testing mode to a small number of users on Android-based devices, but now is available more widely to people on both Android and iOS.
Before the update, the app let users send messages just to their Facebook friends. Now it lets people send messages to anyone with a Facebook account—even if they’re not friends—as long as the sender knows the person’s phone number.
By using Facebook’s network to send the message, it saves the sender an SMS charge, similar to other mobile-to-mobile messaging services like WhatsApp, Snapchat and WeChat, as well as Apple's iMessage.
Mashable also reported the new versions of the app were also built specifically for Android and iOS operating systems, meaning the icons, colour schemes, and layouts were designed to feel more natural on each OS.