A note upfront: It appears that Empathy doesn't support Facebook's messaging service, but Pidgin, a similar multi-messaging client based on the same library
libpurple, does with a plug-in as described below.
purple-facebook plugin is a replacement for the builtin Facebook XMPP plugin. Facebook is in the process of shutting down their XMPP service, which will inevitably break existing support.
The following instructions are written for Pidgin and while they should work for the same for Empathy in theory (since they're both based on
libpurple), people report that Empathy doesn't accept this plug-in for some reason.
purple-facebook in Ubuntu, Linux Mint and derivatives, you can use its official repository. To add the repository and install the plugin, use the following commands:
sudo add-apt-repository "deb http://download.opensuse.org/repositories/home:/jgeboski/xUbuntu_$(lsb_release -rs)/ /"
wget -O- 'https://jgeboski.github.io/obs.key' | sudo apt-key add -
sudo apt-get update
sudo apt-get install purple-facebook
If you don’t want to add the PPA, you can download the DEB from HERE (but you won’t receive any updates unless you add the repository). Or, grab the source and build it yourself. […]
Once installed, add a new account in Pidgin (Accounts > Manage Accounts > Add) and in the Protocol dropdown, select “Facebook”
(important: NOT “Facebook (XMPP)”):
Pidgin Facebook I should also mention that in the username field, you can enter either your emil, your Facebook username or phone number associated with your Facebook account.
(Source with some modifications)
As of October 18, 2015, jgeboski's GSoC work was merged into the mainline Pidgin project. It will appear in the next major release of Pidgin.
This means, future libpurple versions in Ubuntu (and probably earlier in the Pidgin PPA) will include
purple-facebook and supersede the above procedure.