I figured that was what refurbished was.
So if I buy something new, I just want to make sure it says Unlocked, right?
If I buy something new that doesn't say unlocked, then Sprint may not be able to set it up? That doesn't seem right, as in kosher.
If you buy it brand new, they generally are sold by the carrier. There also is an option to buy it SIM free (unlocked), but requires paying off the phone in full. On Apple's site, you can pick which carrier you want the phone from. Or if you go to a store (Apple or otherwise), you pick the carrier. So when I got a 5, I was on Sprint and bought it from Apple.com, selecting Sprint. When I got a 6S+, I went to Costco and got it through Verizon.
If you get it refurbed and unlocked, it can be activated on a carrier that utilizes the same wireless signal. I don't know if this holds true anymore with LTE, but it used to be GSM = ATT and TMobile, and CDMA = Verizon and Sprint. So if you have an unlocked GSM phone, it will need to be on a GSM carrier.
So if you stay on Sprint, and don't want it unlocked, make sure your phone is Sprint. They lock them down to specific carriers.