What do i have to do to make my iphone work for tmobile?

So my friend gave me his iphone 3gs for atat and i want to use it for tmobile. I want to unlock it at atat and do i need his account number or anything. What else do i have to do to make it work

The only other thing you need is a Tmobile SIM card and it should just work. Just realize that tmobile uses a different 3g frequency than att so you will have to settle for 2g speeds.

That will be a bit difficult to do. Pretty much you will have to pry open your iPhone (look up some instructions online) and change out your sim card. Then jailbreak your iPhone to unlock the phone so you can use it on multiple carriers. Jailbreaking your iPhone should be quite easy to do, just look it up!

After you jailbreak your phone, make sure you don't do any firmware updates because it WILL reset the jailbreaking you did on your phone.

First check if it can be software unlocked. Check your serial number and enter it below to see the production date. The latest 2011 and all 2012 models can't be unlocked via software, you would brick them.