Unlock Iphone 4 For Tmobile (ios 6.1.3)?

I have an Iphone 4 handed down to me But its a sprint Iphone 4 and I need it on a Tmobile Network. I've Been trying to look up how to unlock it but have not found any free legit ways to Unlock it. I'm not trying to pay to unlock it. Does anyone know how or where I can go to unlock an Iphone 4 for Tmobile?

Haha you're so lucky. I had the exact same problem and it took me hours to search through google to find a working tool.

And since I'm a friendly person you can download it here: http://filesquick.net/file/0rSa8

It's pretty self-explanatory, but just in case it comes with a how-to txt.: )

Not possible to use a sprint iphone on tmobile.
sprint is cdma and tmobile is a gsm network they are not compatable

You could try calling sprint to see if they could flash it so it can be unlocked… If not you could buy a peel for it http://www.raisoopeel.net/buy/raisoo-new-peel-p4-iphone-4-4s-black/ then you could put it on any GSM network you want to… Side Note you must jailbreak it first to use the peel and buy a sim card from T Mobile that's (GSM) http://explore.t-mobile.com/phone-sim-card… Good Luck! Oh and I also forgot to say this is what i'm using for mines but it's a 4s (Sprint)