When I left for my holidays in China, I made sure to disable 3G on my iPhone 3GS to avoid getting bill shock. Once back in Singapore though, I couldn’t seem to get the iPhone to connect to the cellular network with 3G enabled. It kept saying “No Service”!
This is how I solved it
1. Disable 3G in Settings/General/Network
2. Power off the iPhone by holding the top lock button down and then sliding to power off. Leave the phone off for 30 seconds
3. Power on the iPhone
4. Reset network settings in Settings/General/Reset
5. Turn on 3G
No more “No service” problem now!