Can sprint iphone 4s be unlocked?

I have an iphone 4s and its locked to sprint. Sprint is absolutely horrible, too expensive, dropped calls, poor customer support, and so on. My bill is passed due and i'm wondering if its possible that i can keep my current iphone 4s by unlocking it and moving to a different carrier like T-Mobile. Is it even possible to keep my number?

Not at all. Sprint uses CDMA towers which don't use SIM cards for service purposes. So everything is programed into the phone. T-Mobile uses SIM cards for their GSM service.

Now it's possible, but I don't think there's a legal way of flashing a CDMA iPhone to GSM.