Problems activating phone!

I restarted my iPhone 3gs and got up to the step after I set up my wifi connection- which was successful. Then pressed the "Next" button to activate my phone and it said that it was unable to activate my phone b/c the server temporarily unavailable. It told me to try again after a few minutes or to connect it with iTunes- both of which have not worked. I think this might have a problem because it is an unlocked phone ( I use t-mobile ) Please help if you can.