I have a Samsung a107 GoPhone AT&T Prepaid GSM phone (sim) and Im swapping it over to a Nokia E72 smartphone with no luck. It detects network for 1minute and then it goes blank (no network coverage)... What the heck is wrong?
I went to the ATT kiosk and they told me its because of the coding of the Sim card, but STILL it should be able to let the smartphone pick up the signal.... What is the problem here people?

*Youre under Terms and "Community Guidelines", be smart*