Hi I have upgraded the software from 3.6 to 4.0 on my BlackBerry 7750 and my BlackBerry registration id is wrong. It wont let me change it. Do I have to go back to the 3.6 software inorder to change this.I know I was able to do this with 3.6 but now I cant with 4.0 any suggestions greatly appreciated.

What is a BlackBerry Registration ID?

You have to go into the programming of the device to see it.

AH - a CDMA thing. Not a GSM thing.