I just upgraded to OS 4.2 and my wifi/3g Ipad wouldn't recognize the 3G network. After several hours I discovered the following post over on the Apple Support Forum- worked like a charm (from Dr. Technical
I had 3G problems after upgrading to 4.2.1, with the following symptoms:
- Network status indicator (upper left corner) showed "No Service" instead of "AT&T 3G" (and, of course, no cellular connectivity). Wi-Fi worked normally.
- No "View Account" button on Cellular Data screen in Settings
- Under "About", Carrier and Cellular Data Number showed as "Unknown" or "Unavailable"
I called Apple tech support and went through some troubleshooting procedures. Here's what finally worked for me:
- Bring up the Settings app
- Set "Airplane Mode" on for a short period, then turn it back off.
- Under "General", choose "Reset" then select "Reset Network"
- Confirm that you want to reset all network settings
- Power the iPad completely off then turn it back on