Following what the company describes as a successful trial in Europe, the world's largest social network is going to confine the ability to message Facebook friends solely to the dedicated Facebook Messenger app.

Over the coming days users of both the Android and iPhone versions of Facebook's mobile app will discover that when they receive a message from a friend -- be it a straight text, a selfie or a video -- rather than being able to read it within the app, they will get a notification that a message has arrived and that in order to view it they will have to install Facebook Messenger.

Facebook is yet to take to its official blog to announce this global mobile migration but, when pushed, it did release an official statement to the media, saying: "In the next few days, we're continuing to notify more people that if they want to send and receive Facebook messages, they'll need to download the Messenger app. As we've said, our goal is to focus development efforts on making Messenger the best mobile messaging experience possible and avoid the confusion of having separate Facebook mobile messaging experiences. Messenger is used by more than 200 million people every month, and we'll keep working to make it an even more engaging way to connect with people."

The Messenger app is good. It's clean and intuitive and once installed will launch automatically if a user has the main app open and receives a message.

However, the forced migration means that technically users will be switching between two apps to do things that until now were all possible within a single app. Then there's the issue of choice. It doesn't matter if the standalone Messenger app is good, if people haven't been given the choice of whether or not to install it.

The final potential issue could be smartphones themselves. Not everyone owns a flagship phone with plenty of RAM for multitasking or plenty of free storage space for more apps.