I'm posting this from India, on my own 3g iPad bought in USA, so I do know a few things about using an iPad on 3g outside of USA. A friend brought over a similar iPad 1 bought in USA (with ATT SIM inside) and wanted to get network access on the local ISP here where I live, near Pune India.
This is a bit weird. I put my working local SIM into my friend's USA iPad, and couldn't log onto the local (Idea Cellular) network using the exact same APN, Username and password settings I use. The only difference I can notice between our iPads is that she had never activated the 3g in USA using ATT. I did use ATT for a few weeks before coming to India, and I haven't had any trouble with 3g on other networks. Is there something else required to get 3g active?
I noticed in the settings that her system doesn't include a "Carrier" tab as mine does. It has "Cellular data" and "Data roaming" turned on, but though the system recognizes that there is a SIM inside, it doesn't seem to even try to find the network here. In the "General" -- "About" section it says "Network not available" Do you have to go through the ATT activation process before leaving USA to get 3g working? Seems a bit strange if so since others on this forum seem to have been able to take a USA iPad out of USA and successfully log onto foreign 3g networks without ever activating an ATT account in USA first.
Any suggestions most appreciated!