Best answer by Gregor
Porting your number doesn't have anything to do with registering your account.
Did you download ID Mobile app on your phone? Try downloading it and registering through there.
When registering your account are inputting your temporary ID number or your old number that you want to move over? You should input your temporary ID number there.
Do you have already any account registered with ID before? If yes, then you should use different email address.
Try these steps above and let us know if that helps.