Facebook aims to replace texting
Facebook has launched an instant messaging service for mobile phones, similar to BlackBerry Messenger.
The dedicated app, for iPhones and Android devices, allows users to contact individual friends or groups of people.
Its release comes a month before Apple is due to unveil a similar product.
Attention has been focused on mobile messaging recently because some of the London rioters were known to have used it to co-ordinate their movements.
So far Facebook's mobile messenger is only available in the United States, but it is expected to eventually roll out in other countries.
The social network's 750 million users already have the ability to send messages through the website, and on Facebook's original smartphone app.
Its new application adds the option to send directly to a mobile phone via SMS, and also to include location information.
Facebook's timing has raised a few eyebrows within the industry, given the debate around BlackBerry Messenger's role in the recent UK rioting.
However, it is likely that its decision to launch in the US now was influenced by the impending Arrival of Apple's iOS 5 and its integrated messenger.
Stuart Miles, the founder of Pocket-lint.com, told BBC News that Facebook might be able to make mileage out of its compatibility with more than one phone system.
"Apple will be iPhone to iPhone, like Facetime. The same as BBM which is Blackberry to Blackberry. [Facebook] will be Android to iPhone, so theoretically it can only benefit from the platform," said Mr Miles.
"The big question you have to ask is how long will it be before Google+ has a messaging service built-in."