While previously users had to sign up for Messenger with their Facebook accounts, now, in a few countries, it can be done with just a mobile telephone number. In the U.S., Canada, Peru and Venezuela, users who sign up this way can allow the app to sync with the contacts on their phone so they can easily find people to message.
Along with the phone number, the user's name and photo are still needed to complete the sign-up process.
The same features will be available in the app under the new sign-in process, Facebook said in its announcement, including photos, group chats, voice and video calling. The change applies to Messenger's app on iOS and Android, and the new sign-in feature might arrive in additional countries later.
Messenger currently has more than 700 million users who log in monthly, which is roughly half of Facebook's total monthly user base. A good chunk of Messenger's growth could be attributed to Facebook's decision last year to force users to download the app for mobile chat.
Still, the new Messenger sign-up process could attract more people who don't have Facebook accounts. Messenger is becoming one of the social network's most important products.
At the company's annual developer conference in March, Facebook said it was turning Messenger into a platform for other apps to integrate their software into Messenger. Messenger users can now also send each other money, and interact with online retailers through the app.
And, Facebook recently changed Messenger to give users more granular control over location sharing. Facebook hinted that the change could potentially make way for integrations with ride hailing services like Uber.
Having more users will help Facebook to monetize the growing array of services available in Messenger.
Zach Miners covers social networking, search and general technology news for IDG News Service. Follow Zach on Twitter at @zachminers. Zach's e-mail address is zach_miners@idg.com