CDMA and GSM networks are two types of cellular phone networks. Generally, if you have a phone made for one, it can't be used on the other.
In the US, Sprint and Verizon run on CDMA networks while AT&T and T-Mobile run on GSM networks.
If you are interested in purchasing a cell phone, be sure to verify that it is unlocked for the correct network!
If you want to know more about CDMA and GSM, check out our article below!
If you're not sure which one you need the best way to know if a phone will work for you is to contact your carrier directly and ask!