Here's my situation. I'm on a family share plan, and 2 of us have iPhones. The two of us also have unlimited data. The other 2 have dumbphones. If the 2 dumbphones upgrade to a smartphone, and then transfer the phones to the 2 of us with iPhones, will we be able to keep the unlimited plan? Also, does anybody know if upgrading from a 3G unlimited to 4G unlimited is possible? Does the plan automatically change with the 4G phone?