Unable to access 3G and GPRS after upgrading iOS 4.2.1

[Emerican]

I have iPhone with me. I have upgraded iOS to 4.2.1.I can use Wi-Fi. But I am unable to make use of GPRS and 3G. A message is prompted ''could not activate cellular data service''. When I try to install APN but I am unable to do the same. It shows APN is already installed. In fact there is no APN installed in my iPhone. My work is pending as I am unable to access my 3G service in my iPhone. Please help me out of this problem and provide me appropriate solution so I can continue with my work. I am waiting for your prompt reply. Thanks a lot!

[Abenaki]

You can perform following steps I think it will help you out. Windows users should browse to "C:\Users\User Name\AppData\Roaming\Apple Computer\MobileSync\Backup" You should move Back Up files to other folder.Conncet your iPhone and take back up. Once back completed disconnect your iPhone . Under back directory you should copy the new folder at different location and name as New. Once the copying of the folder is completed you can delete the old folder from the Backup directory. You should perform full restore. Once completed the iTune will prompt you restore from a backup that you select a new configuration. You should not select any uncheck all synchronization boxes. You should also uncheck Applications and Data. Back up iPhone. Recently back folder should be deleted. You should copy the back up into Back Up folder from the Old folder. Once completed Select and delete folder"8218978e4ab0a48035bb92653145a6be872ea858". Restore iPhone using right clicking in iTunes. Once completed with restore iPhone will synchronize with computer and it will restore the application automatically. Once finished with synchronization move to New Folder in the Back up folder. Its name is changed with random characters. Copy files from randomly named backup from the New folder to the MobileSync\Backup\Randomly Named Backup. Files are Manifest.mbdb", "Manifest.mbdx", and "Manifest.plist”. Again perform the “Restore Backup" in iTunes. An error will prompted restart your phone. Now check you can access 3G, GPRS services.

[Crespin]

According to your situation I can tell you solution that will fix your problem. I was using fake APN in my past since I was unable to to access GPRS. It shows APN is not installed in my iPhone. I have updated my iPhone to iOS 4.0. Now I can acess GPRS in my iPhone. I suggest you to update your iPhone with iOS 4.0. Most probable it will work in your situation. If it does not work you can also search in other forums.

[Odalis]

I know it is very irritating when you are unable to access internet in your iPhone. You cannot do routine work easily without an Internet. I will tell you some simple steps that you can try. You have to reset all settings in your iPhone. Tap Settings in home Screen. Select General under Settings tab. Select Reset. Tap on Reset All the Settings .Your iPhone will reset all the settings. All the Data Stored in your iPhone will be deleted. You may take back up of all the data before resetting. Hopefully it will help you out!

[switchblade327]

Well I can give you another solution to rectify your problem. This solution is applicable to users who are using Mac. You must uninstall custom profile from the settings. You have to take full Back up of your iPhone. Navigate into Back up Directory ~/Library/Application\ Support/MobileSync/Backup/random-backup-name you should delete file named 8218978e4ab0a48035bb92653145a6be872ea858 .You should now restore your iPhone. Once finishes it will prompt an error message. Ignore that error message. iPhone will synchronized with all Application . I think your problem wiil be solved.

[Illinois]

You can solve this problem by installing carrier settings in your iPhone. Well you to download the settings and install the same. You have to Select Settings from the Home Screen. Search for the General tab .Select About in General tab. A message will be display in your screen. It will ask you to update Carrier Settings in your iPhone. Select Ok and let the iPhone update the Carrier settings. Once it finishes you can install the updated settings into your iPhone. Reboot the iPhone and whether you can access internet or not.