How to unlock Sprint iPhone 4s to T- Mobile Carrier?

Well, I have T-mobile without a data plan on my current phone. I recently bought an iPhone 4s from a friend who has Sprint. However, I have heard it is really hard to unlock it! I don't need to have a data plan on the unlocked phone, i just want to have call text and Wi-Fi. Also, I heard the sprint store might unlock it? I'm not very good with technology, so thank you for the help!

When we wanted to use an at&t iphone 4 on t mobile, we had to have the original iphone owner call at&t to request to have it unlocked. They gave her instructions for the process which takes a few days as they have to be sure the phone's been paid off by fulfilling a 2year.contract. After they figure it out, they email the owner who follows their instructions to unlock and reset it to factory specs.

Then you can take it to another provider, like tmobile, and they treat it like a new phone.

If the iphone has a sim card slot it can be done at http://payobill.com or 1-855-PAYOBILL.COM