Typically the problems using a CDMA phone with a GSM Sim card are no LTE and No MMS. I know people say there are some workarounds but not sure how successful they have been. I have tried (unsuccessfully) to do this with an Ativ SE using an AT&T Sim. Granted this was a Windows phone but I don't think android is any different. Certainly not an expert though. Just my experience. What I ended up doing was purchasing a Straight Talk Verizon kit and it worked fine with LTE and working MMS.