Full Signal Bar but No Carrier Name Fix when Using GPP SIM Unlock for iPhone 4S

If you’re an iPhone 4S user who’s been using GPP SIM to unlock your iPhone 4S on iOS 5.0.1 or 5.0, you may encounter this issue whereby you get a full signal bar but no carrier name is being displayed.

GPP SIM is another SIM interposer device similar to Gevey Ultra S developed by GPP Team in China to unlock iPhone 4S on baseband 1.0.11, 1.0.13 and 1.0.14. It also provides untethered unlock for iPhone 4S without the need to jailbreak.
I was experimenting with a couple of things today with an AT&T locked iPhone 4S and at one point, I had to reboot the iPhone. However, after the phone rebooted, it was stuck on ‘Searching’. When I checked under Settings, I was able to see that China Mobile was already showing as the carrier.
After toggling the Airplane Mode, it was showing full signal bars but no carrier name was showing. When I tried to make a call to another test phone, I can’t hear anything from the earpiece but that test phone was showing my incoming call. I sent out a text message, the other phone received it but the 4S was stuck on sending out text message status.
I tried to reset network settings countless of times and also tried to reset all settings twice but to no avail. I didn’t attempt to do a full restore because there’s no way to keep the current iOS 5.0.1 as Apple is no longer signing this iOS version. By updating it to iOS 5.1 it will render this iPhone useless. A quick search on Google returned this result which is widely discussed on Apple’s forum. Apparently this seems to be a bug with iOS 5.0.1 and many believe that it has been resolved in iOS 5.1. I also switched SIM cards but nothing worked.
OK, let’s cut to the chase. How did I fix this? Thankfully it’s pretty easy.

1. Reboot the iPhone 4S.
2. As soon as it boots up it will immediately start searching for the network.
3. Wait for a couple of minutes. Just make sure that it’s still on ‘Searching’ mode.
4. Toggle Airplane Mode and you will see full signal bar but no carrier name.
5. Go to Settings > General > Network and turn on Cellular Data Network. That’s it! Your carrier name will show up immediately and you can start making calls again.

This is probably too trivial but I shouldn’t have jumped into conclusions and start troubleshooting without trying the basic steps first. My bad. I hope this will help all GPP SIM users out there.