phone for a cingular plan because i dont want to lose my ring tones or games that i downloaded

Yes, you will need to get your phone unlocked by t-mobile first and also get the unlock code. You will want to call customer service and request to have it unlocked BEFORE you close your account, they will only do it on active accounts.

You may not want to tell them why you want it unlocked, since you are planning on switching providers. The main reason they have that feature is for when people travel to other countries and need to be able to use their phone with companies overseas. Good luck!