This was announced by Facebook’s David Marcus in which he wrote, “Excited to announce that the ability for everyone to use Messenger, even without a Facebook account, is now available globally. Sign up with your phone number and try it out!” Basically what this means is that like other messaging apps, all you need is your phone number and full name and you can register for the app and start sending messages to your friends.
However it should be noted that if you choose to sign up this way, you will not be able to message your Facebook friends, not unless you know their number. It will also not be a global account, meaning that you won’t be able to pick up chats from different devices/platforms, like moving from your computer to your phone or to your tablet.
That being said, this might come in handy in emerging markets where Facebook accounts might not be popular, but the need for messaging apps are.