First off, I have trouble believing the T-Mobile rep told you to get your phone unlocked, since that lets you leave their revenue stream. I easily believe he/she told you to simply dial the international code for the U.S. when calling home, since that keeps you on their dime.
Here's the thing about getting your phone unlocked: Right now, making calls with your current SIM card from overseas, all your calls are on T-Mobile roaming rates, which at international levels are pretty expensive. But if you get your phone unlocked AND buy a local SIM from a local phone provider, then you're now paying local rates, not additional international roaming charges. then when you're done, and back on U.S. soil, you can plop your original SIM card back in. See, the SIM card is what identifies you to the network, and unlocking your phone lets you use whatever SIM you like in your phone.
I'm thinking of purchasing a Razr. I will be traveling to Africa. Can anyone tell me what do I need to do extra to the phone..a T-Moble rep told me nothing just dial international code for the U.S.A, but do I really need to get it unlocked?
Or can I just use "as is" with my Sim card here from the U.S.A?