T-Mobile USA is now allowing U.S. customers to use their service without any annual contracts. You'll get some better deals if you sign a contract, but if you don't want to be tied to T-Mobile, you now have that option.
Several years ago, it seemed that several wireless carriers were trying the "no annual contract" tactic. I guess it either caused too many problems or they lost too many customers. I'm surprised to see that T-Mobile is jumping back on this wagon, but maybe it's a recession-special that's only going to last a few years.
If you're a medical student and you're not sure about your financial stability as a student, then maybe you may want to leverage this "no contract" option. After all, you don't want to spend all your money on mobile phone bills.