I recently bought an Iphone 6 plus used and after i installed it and was able to make calls. i kept getting a message on the phone saying, "Iphone is not Activated. contact your carrier if it continues" which it's Verizon. This pops up every 15 min. or so. I contacted the owner and he said that he had no problems. Apple doesn't even know how to fix it. I called verizonwireless and she told me she has no clue. Any help would be appreciated. Thanks.