If you have a 3G phone, and then get a 4G phone, and switch them around on the same line (just to play with both), don't switch them more than 3 times in a month. Verizon will de-activate the SIM card on the 4G, and you cannot get the phone activated again until the next billing cycle. Their reason is "excessive switching". I think that we should be able to do this as much as we want, as it doesn't hurt them in any way. I was doing this with my Maxx and an iPhone, and now have to wait until August 16 to use my Maxx again.