4G *doesn't* use *228. LTE devices' SIM cards automatically update their PRL (you can force an update by restarting the device). I've heard that *228 will damage LTE devices, but I can't see how. You can switch between two LTE devices by interchanging their SIM cards (it's spookily easy). However, the SIM in your Charge is associated with a specific ESN (mobile number) in Verizon's system, which is why you have to call them whenever you want to reassociate the SIM with a new ESN. I know, because when Costco sent me my charge, they associated the SIM with the wrong ESN and I had to have them send me a new one. -.-