Normally, you should have BB service activated.
Download and install Facebook Apps from BBworld.
You then have to follow through with Facebook chat Apps. Both Installs automatically.
Log in to facebook, and you should be in FB 24/7.
Hope this helps.

Same with Yahoo messenger :-)

Again, make sure BB service is active. I have noticed though, that Vodafone BB service is consistently ON (BB logo is always present) than Qtel.