Apple’s new iPad 3G is basically unlocked, so you can theoretically use it on any mobile phone network. There is just one problem is uses a new type of SIM card, a Micro SIM which is only available from AT&T at the moment.
Luckily you can make your own Micro SIM using a standard SIM card, you can find out full details on how to make your own Micro SIM over at Tech Radar.
As you can see in the video below, a Micro SIM has been made using a full sized SIM card from T-Mobile, and after a few tweaks (details below), the iPad 3G is running on T-Mobile’s Edge network.
You will need to follow the instructions below if you want to use your iPad on T-Mobile.
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 “APN” field:
* wap.voicestream.com
* epc.tmobile.com
* internet2.voicestream.com
* internet3.voicestream.com
iPad Insider via Gizmodo