the clause Sprint says about buying 1phone 6 & no guarantee it will work with 3rd party

[Doreen_1]

Why does Sprint say you can't take your iPhone to 3 3rd party no guarantee there SIM might not work. They won't realise if they we're bought around Feb. Need answers

 

[Titillating]

Sprint and Verizon are CDMA networks. Phones for these networks are built to those specifications, which are different than the GSM networks that the rest of the world uses. There is a lot more crossover and dual compatibility these days, but it is still not universal. Sprint cannot guarantee that a Sprint branded phone will work with other networks, because those networks might be using a frequency that the Sprint phone cannot use. This is especially true if trying to use a CDMA phone outside of the United States.