Above SIM card info. is for your reference if you are planning to unlock iPhone 4 and use it with another carrier. Currently, T-mobile does not offer Micro-SIM cards which is required by iPhone 4 (also iPad). Even when there is a solution to unlock iPhone 4 in the near future, you will need to be prepared to cut your SIM card base on the above spec. of Micro-SIM card. There is proof on the internet that iPad is able to use the EDGE service from T-mobile while there is no way to use the 3G service due to the different frequency from AT&T
|T-Mobile USA Network|
|AT&T USA Network|
|iPhone 4 Supported Frequency|
|EDGE||GSM/EDGE (850, 900, 1800, 1900 MHz)|
|3G||UMTS/HSDPA/HSUPA (850, 900, 1900, 2100 MHz)|
Just in case you still want to do it and you know what your are doing, You can try to use T-mobile EDGE APN Setting as followings.
DISCLAIMER: We have not tested this, so this information may be inaccurate or incomplete. alohaeveryone.com will not be responsible for individuals following the instructions on this page. And users are doing so entirely at their own risk.