Iphone 3g 4.1 fw jb bb No Service problem

[hoodbran]

Here's my problem, Im really hoping someone can help!?

Got a locked o2 iPhone 3g.

I jailbroke it using redsn0w AND changed the baseband to unlock it.

Downloaded ultrasn0w via cydia, unlocked it.

Inserted new SIM, worked, except 3g didn't work. I tried looking for APN settings on iPhone, some website suggest to restore with new SIM in via iTunes so to get new carrier settings as APN is hidden? Anyways, I did that then experienced a bunch of 1015 errors.

I used redsn0w to place the phone in pwned DFU mode.

Connected iTunes to let it do it's bit (restore, then 1015)

I then used tinyumbrella to kick it out of restore.

Then used redsn0w again to jailbreak again and it worked.

HOWEVER, there is one dot of a bar followed a few seconds later with NO SERVICE, wtf?!

Please someone tell me there's a fix for this, or should I take it to a phone shop?

Ideas?

Update:

I got it to work again on the "home" network (o2) by activating thru iTunes. I'm now trying to jailbreak to install cydia (icon not there) anyways, see if this works....

OK, this IS working now, alas still can't change APN settings for my new network, orange.

The phone is 4.2.1 BB 06xxxx