I don't know much abut gsm/CDMA networks or what phone us on what network tower(s). I bought a used verizon samsung s4 cause I was told it works w/tracfone. Idk what towers they run off of. I see where some ppl can go in their phones and change it from gsm to CDMA or vice versa, Idk if I need to do that, or can do that to get it to work w/tracfone and wouldn't know how if it's possible.Help please.