im looking at buying an iPhone 6plus on eBay. I already have a SIM card from my iPhone 5C with Verizon. I see there are different carriers on eBay. Since I already have a Verizon SIM card can I just take that out of the 5c and put it in the 6 I'm buying? Also could I buy a iPhone 6 Plus for sprint and put my Verizon sim in it? Just kind of confused how this all works. Thanks for the help!