As long as they are the same size SIM card you can swap the SIM freely and use the phone it's in to it's full extent. However, say you get the Note 3 and the first time you power it up and activate the phone with that SIM, it will now be in the system under your phone number. When you move your SIM back to the Maxx it will still work but won't switch the phone on VZW's end. Really not the end of the world but if you need technical support or something it could make it confusing. You can always update it on the myverizon section.