I got my iphone last week. i face 3g internet setting problem with iphone 3g. when i get it first day, it seem OK. But this week it can't access internet with 3g line. I try to do the setting but something missing.
1. Select Settings and scroll to and select General.
2. Select Network and
select Cellular Data Network. <-- i can't find the Cellular Data Network on the phone.
3. Select APN and enter unet.
4. Select Username and enter maxis.
5. Select Password and enter wap.
6. Select Network to complete.
7. Press the Center button to return to the main menu.
8. Your phone has been configured.
Thank You

2.
Maxis APN Settings Not Available? No Carrier Signal?Maxis APN Settings Not Available?
The technique of entering gibberish on the APN column might not work on the maxis network network anymore (since they are now the official malaysian carrier). Please follow the guide provided below:
1) Start up your iphone with non maxis SIM (digi, umobile, celcom)
2) Once started, you should be able to go to the (General -> Network -> Celular Data Network). There is where u can key in 'disable' to disable the 3G/EDGE. But wait, don't key in yet with ur non-maxis card still inside.
3) Back to the page where u can still see Celular Data Network, right now, eject your SIM card and swap it with your Maxis SIM now. Once swap it in back, only tap the Celular Data Network.
4) If you previously have updated the Carrier Settings, now you will still be able to put in disable or some other words other than unet, maxis or wap. Once everything is key in, go back to your home screen. Time for testing. Test the Weather channel, Safari etc.. You will received the error, you are not subscribe to the celular data network service etc.
(credit to cool_alvin83)
No carrier signal and can't call out?
For those of you who has lost signal after jailbreaking, simply plug in your phone and start iTunes, press option-click(Mac) or shift(Windows) + press "Check for Update. Select the file type as 'iPhone Carrier Configuration Files (*.ipcc)' and browse to the 'Maxis_my.ipcc' file you've downloaded and extracted from Malaysian Telco Carrier Logos thread.
http://forum.lowyat.net/topic/790913/+1880#entry24726513(credit: bearbearhong and ZipD)