kmoser,
Verify that your phones IP is not on the IP blacklist due to the previous incorrect ID and password issue. Also verify that you are using the correct dial code, 1+ the number or just the number or some type of combination, whatever you had setup for outbound (see outbound rules). For incoming you have to verify your DID's are listed in the system as usable.
Just a quick tip, for Polycom phones you can do reboot and reformat (not recommended) of the phone at the phone itself. You can also do a reset, which I think works best for clearing the phone without having to reload the software. It will still pickup the config file, if your provisioning from the server that is.
At the phone hit keys 1+3+5+7 (simultaneously) and then enter password 456 (default passcode). Takes about 2 minutes for phone to come back up.