is it possible to unlock a phone from tmobile using at&t?

theres this phone i want really bad but since my phone is in a contract i cant get it anymore and we have a family plan with 3 lines and in total they would charge my mom like 200 just to get rid of my phone and my mom too wanted a phone from tmobile. i hate at&t i only got it because i had no other choice. i had just gotten the phone about 3 months ago and ive been tired of it since about 3 weeks after i bought it. ive been wanting the samsung gravity white and aqua for about a year and a half now! my friend has it and iim so jelous! is there any way i could unlock the samsung gravity with at&t? does at&t unlock other companies? i heard it does -thanks

AT&T wont unlock cell phones locked to some other network. You have to get it unlocked either from AT&T network or from any other private vendor. For example, you can get the unlock code for your Samsung Gravity phone from Unlocking4U.com at affordable cost with an easy unlocking guide. Good luck.