For those who have upgraded to iOS4 and internet isn't working

[HBKid]

I also had this problem since I upgraded my 3GS on Thursday. I did a full restore from a backup, and my internet still wasn't working. Like others, my WiFi was working though. From information I gleaned, it's either corrupt APN settings, or I think in my case (I checked and my APN settings were blank), that updating it just deleted them altogether.

On your phone tap Settings > General > Network > Cellular Data Network.

If it's all blank like mine, you need to find out your carriers APN settings and input them. Restart the phone, and it should work.

 

[notmymac]

Except if you are based in the US and have a locked phone...AT&T does not allow you to edit the APN settings..

At that point it is backup, sync, restore as new, then restore from backup or resync...

 

[HBKid]

Ah. I'm from the UK so I didn't know that, but I'm sure this will help out some unfortunate people elsewhere.

 

[nebo1ss]

Except if you are based in the US and have a locked phone...AT&T does not allow you to edit the APN settings..

At that point it is backup, sync, restore as new, then restore from backup or resync...

You can update the APN settings on a locked phone. You use Safari on Wifi from the phone and go to the following web site help.benm.at find the country and carrier you need "including ATT" download and install the apn settings.

 

[draz]

Alot of helpful tips in this thread:
https://forums.macrumors.com/threads/944733/

Check out Page 2, some great tips there

 

[notmymac]

You can update the APN settings on a locked phone. You use Safari on Wifi from the phone and go to the following web site help.benm.at find the country and carrier you need "including ATT" download and install the apn settings.

Meh..wish I was able to tell people that when they are calling...But can't as it is not an "official" Apple response....yet another helpful tip I can't pass along..but good to know..Thanks