With Sprint???
No you can. You must pay the phone off. Request it to be unlocked. And all this must be done through Sprint only. Sprint doesn't like to unlock their phones, even once paid off. You really have to stay on them 24)7. Then you'll get an email verifying is been unlocked, usually takes 72 hours. Also an S8 is a good phone another carrier that's CDMA would like to activate for you. Verizon is tricky. Boost will do it. Also Cricket I think. Forget about Metro and T- Mo.
You just have to research it and you'll find another carrier. Forget about Xfinity as well, 2 times.