I will be staying in Lansing/Mi at the Uni for 3 months and was wondering which provider/tariff to use for my stay. I've got an unlocked iPhone 3GS. I've only got the choice between AT&T or T-Mobile, because the others are CDMA not GSM, right? Is it possible to get a sim only, bc I've just seen pre-paid phones on the websites. I obviously don't need the phone. Is it true you have to pay even if you GET the call?? I will be using around 100min (calling), 50 SMS and 200MB data per month. Thankful for any suggestion.