Jun 4, 2011
Eversince I upgraded my note 2 to Ver 4.3, I can't make or receive any calls. Evertime I dial a number I get this message "NOT REGISTERED ON NETWORK".

Eventually I had to go to the Samasung service center and they also said that mine was the 4th phone they have received since morning with the same problem. So I repent having upgraded to 4.3

Something is terribly wrong somewhere.
OH I am sorry styropax. Sometimes upgrades do some crazy things to phones. It's not exactly the upgrade's fault. They can't foresee every variable on every Note 2 when they write the upgrade. I've dealt with similar problems as yourself after a major upgrade. I eventually had to factory rest the phone to set things right. It worked flawlessly following the reset though.. and was faster and used less battery. In any event, you will want to check in with the other Note 2 users to see what they might recommend for fix. Here is a link to that area: Samsung Galaxy Note 2 - Android Forums
Best of luck to you and I hope you enjoy your time here at Android Forums.