Upgraded to 2.1, lost NAM2

[adityasa]

Hello everybody,
first of all, i'm a newbie here. forgive me, if i post a new thread in the wrong forum. if so, you are welcomed to move this thread to the appropriate forum.

secondly, i've been googling for this topic everywhere, and found nothing. it seems this topic is very rare. so, here i am posting this topic here.

here's my problem. i have a sprint htc hero. the first time i had it, i was able to see NAM selection menu (NAM1 or NAM2). but then, soon after i upgraded from to 2.1, i can't find that menu. now, i only have one NAM. the reason why i want to have NAM2 back is that i'm currently overseas. i want to add a local carrier number, so it will be practical to interchange carrier.

is it possible to revert the firmware to where it was, so that i can have NAM2 again?

Regards,
Aditya