For those who are extremely crazy, bored or brave there is a new DIY trick out there to get an iPad 3G running on T-Mobile's Edge Network. As Apple has said, the iPad isn't locked to a specific carrier, the problem is that the iPad doesn't operate on the same frequency band as most of the major 3G carriers.
Someone has figured out a way to work around that using a SIM card on the Edge plan. Of course, it hasn't been tested by any of the gadget blogs out there. It involves physically cutting down your SIM card. It's probably not worth the trouble, unless you have a grandfathered $5.99 T-Zone data plan. Or just feel like being brave.
Either way, let's get this out of the way: iSmashPhone claims no responsibility if you have the cojones to try this DIY method. That said, here are the steps.
1) Have your iPad 3G and T-Mobile SIM with EDGE data plan ready
2) With the SIM eject tool that came in the box, take out the AT&T Micro SIM and place it on top of the T-Mobile traditional SIM, trace it and trim it with a scissor or any other tool that can get the job done right (Be sure not to cut the gold contact). Or follow this guide from Techradar.
3) Insert the DIY T-Mobile Micro SIM in the iPad
4) Turn off WiFi
5) On the iPad, go to Settings > Cellular Data > Turn Cellular Data ON
6) Turn ON Airplane Mode and then OFF to refresh
7) You should be on T-Mobile EDGE at this point, if not go to Settings > Cellular Data > APN Settings > And try these on the ‚ÄúAPN‚Äù field:
via iPad Insider