I have a Vodafone sim - when it's in the phone I have a data connection and can browse the net but when I try to call/text it says 'Not registered on network'. I have tried my sim in another phone and it works fine there.
So I tried a 2 Degree's and a Telecom sim in the Galaxy and they work perfectly. So weird.
I did it under 2.3.6 so I updated to 4.0.3 using system update on the phone
Baseband is: N7000XXLPT
SMP PREEMPT Tue May 22 11:17:48 KST 2012
Build Number: IML74K.XXLQ2