Hey all. I'm no expert but I'm working with our network admin to get this resolved. Our IPC 2.0 and 2.1 users can make any call until they either start their unified video or select the IPC option "optimize for low bandwidth". When either of those happens, they will receive fast busies on external calls, but internal extensions still work.
Thanks for any help or suggestions, and let me know any further info that will help.