iPhone 3GS - Restore from Backup = "No Service"

[Hintry]

I'm trying to help someone troubleshoot a 'No Service' problem on their unlocked iPhone 3GS (OS 4.01, Modem Firmware 5.13.04).

It's the strangest thing... about 4 days ago (seemingly out of the blue) the phone gave a "No Service" message.

I initially tried most of the obvious things described here.

Troubleshooting "No Service" messages on iPhone, part 2

I then backed up the phone and did a clean restore. It works 100%

But as soon as we restore from the backup it goes back to "No Service" message

I assume there's something in the backup that's corrupting Network Carrier settings.

I've now also jailbroken using jailbreakme.com and ran Ultrasn0w to try unlock Carrier settings - but to no avail.

Anyone have an idea how to solve this?

[queinnel]

Well, make your turn off 3G network and put the sim card back. That will work.

[Hintry]

You sir/madam are a genius. I did the following:

1. Removed the sim card
2. Disabled 3G (Settings > General > Network)
3. Reinserted sim card
4. Renabled 3G (still didn't work)
5. Turned Airplane mode OFF
6. Turned Airplane mode ON

Works!