Facebook on Monday announced that its Messenger app has hit the milestone of 500 million monthly active users, growing steadily from 200 million active users in April

"This is an exciting milestone but with a half billion people relying on Messenger to communicate and connect, it is also a reminder that there is so much left for us to do," said Peter Martinazzi, Director of Product Management, Facebook.

The company recently separated Messenger from the main Facebook app and made it mandatory for all users to download the Messenger app to continue to enjoy messaging services.

Facebook CEO Mark Zuckerberg recently, during a Q&A session with users, acknowledged that asking more than a billion users to install a new app was not a decision that had been taken lightly, but that he believes that with the two apps users will enjoy a better experience. "...messaging is really important. Each app can do one thing well."

As a standalone app, Facebook Messenger allows users to send videos, stickers, make free calls, chat with groups and more. Facebook says that with Messenger "it focused on one use case - messaging." The company claims to have also improved the speed and reliability of the app, and ships updates to the app every two weeks.

"Messaging is an important part of how people stay connected and since Messenger launched in 2011 we've been passionate about giving people a faster and more expressive way to communicate," added Martinazzi.

In August, the popular messaging service, WhatsApp, which is now a part of Facebook, crossed 600 million monthly active users globally. The company saw a 100 million active user growth in about four months from 500 million active users in April.

WhatsApp also offers similar services to Facebook's Messenger app except that it is yet to integrate voice-calling feature to it. The feature is in pipeline, but has been delayed to the first quarter of 2015.