Facebook shut down their XMPP service earlier this year and because of
this, Pidgin/libpurple no longer supports Facebook Chat. For those of
you who want to use Facebook Chat in Pidgin, there's a new plugin which
makes this possible, called
purple-facebook.
sudo sh -c "echo 'deb http://download.opensuse.org/repositories/home:/jgeboski/xUbuntu_$(lsb_release -rs)/ /' >> /etc/apt/sources.list.d/jgeboski.list"
cd /tmp && wget http://download.opensuse.org/repositories/home:/jgeboski/xUbuntu_$(lsb_release -rs)/Release.key
sudo apt-key add - < Release.key
sudo apt-get update
sudo apt-get install purple-facebook
Working from email as username 08.01.2016
http://www.webupd8.org/2015/08/use-facebook-chat-in-pidgin-with-purple.html