Every time I want to join a channel on a jabber account using bitlbee I'm a bit confused and have to search the whole inter-webs before actually finding out howto configure my chat setup to do so.
My online search points me out to the bitlbee wiki. Nevertheless those commands never got to the point to have it actually working. After many attempts a colleague pointed me to the right solution.
To never forget it anymore and sharing the working setup with the world I summarize it in this blog post.
In your bitlbee control channel &bitlbee :
chat add [account id] firstname.lastname@example.org #room /j #room
As you can see in the chat add command the ending #room was missing in the online documentation.
Hope to tackle many frustrations by this one :)