Apple ipod

IPhone 3G baseband downgrade?

what happens when I come down from 3.0 beta 3 back to 2.2.1? I tried with my laptop and get the error message that mid-1013 by the downgrade? What I can do? I've tried everything "to ignore the error 1013 and jailbreak, but when I jailbreak, I do not receive any service. I need this phone today. Someone please help me if. I remember trying the whole process on another computer and it worked. but I can not wait that long, because I need my phone. please help

try this link

iphone no service error fix worked 100%