So I updated my iphone 3g to 4.2.1 using redsnow and updating it to the ipad baseband 6.15 blah blah blah... after I downloaded ultrasn0w from cydia to unlock... Now problem... I popped in my simple mobile simcard and it stays on searching or no service, also tried with tmobile sim card and same problem... any fixes?
if you still get only 1 bar/no service you could try rebooting it until it works, maybe 4-5 times? Worth a shot if you haven't tried multiple boots already. Just make sure 3g is turned off as well.