You can join a session directly from a web link, from within the Blackboard module and from your phone. Collaborate can be joined on or off-campus in the same way, through a web browser (Google Chrome recommended).

From a weblink: You have been sent a link to join an individual session or to log into the Collaborate Scheduler. Open the link in your browser and either join the session or sign in to the Scheduler.
From your module Blackboard: Open Collaborate from inside your course. It opens in your learning management system.
From your phone: If offered, you can use the telephony feature to communicate with other users.