Help with Unlocking a 3G on 4.2.1

So Im trying to unlock a 3G on 4.2.1 so I can sell it. I have used Redsnow to do the jailbreak. Then I installed ultrasnow.

Everything seemed to work fine. As soon as it booted up, I got a notification that there were voicemails so I assume the SIM is working. But then it gets stuck at Searching or No Service.

Any ideas?