The new service will bring competition to Skype, allowing users to hold free video and audio calls with one another through the browser-based and mobile versions of Facebook.
Orange is powering the service with the same technology behind the Libon iOS instant-calling application, with France earmarked as the first territory to receive it next summer.
"By connecting its Party Call service to Facebook, Orange will be able to offer customers a truly personal experience. It is a great example of how companies can use Facebook's open developer platform to make their products social." TechCrunch quotes a Facebook spokesperson as saying.
"We are really happy that Facebook is transforming telecoms just as it has gaming, music, video and numerous other online services."
The news has reignited rumours of a Facebook-branded smartphone, with Orange touted as a potential partner for the venture.