I currently have an I-phone4 and my contract is up. I want to get a Samsung Galaxy note 2 or 3. Can I buy a used phone, either from Verizon or elsewhere, and stay on my current plan, which offers unlimited data. Would Verizon buy back my I-phone 4?
Yes, you can 'bring your own phone' and keep your current plan. Just ensure that the phone is Verizon branded with a clean ESN. Verizon has a trade-in program, but you probably would do better selling your phone on ebay or swappa.