I don't know if this is get buried or not but I worked at Verizon for 5-6 years and can shed some light as to how this can happen . Throwaway obviously because of identity. It basically starts at corporate level employees or indirect retailers having access to all your info when you sign up for service and upgrade your devices. 

  Some employees give out such info to make a quick buck to individuals who print fake ids using that info. Then after they have all the info that they need, the scammers will call Verizon and tell them that they wanna add an old phone to their account for their kids or something. Then they go to other retailers such as Apple, Best Buy etc. and "upgrade" the old phone to the newest iPhone under device financing. They end up paying just the taxes on the device when they upgrade in such manner and always use cash to pay for taxes,so it can't be traced to a credit card. They take that phone and sell it on the black market for a couple of hundred dollars cheaper a to smaller wireless store who then either resells it or sends it overseas. The incentive to them is that all of Verizon 4G LTE phones are bandwidth unlocked by default. It includes iPhones as well. They can use those phones overseas at no cost to unlock it . 

  Apple and Best Buy won't refuse them a phone as it is stated in their policy that if the requirements are met , people can upgrade their  phone, no questions asked. Those fake IDs are so well done , that sometimes , you can't tell by looking at it . They also bring a fake Comcast bill, doctored to look legitimate as it can be presented for a secondary verification . I would alert Verizon and tell them to freeze your upgrade as well because Verizon doesn't check your credit on upgrades usually. They go by payment history for the most part. Atleast you are aware of it. That's the biggest part. I work at Apple and I see many people get ripped off because I can't say no. Some people end up walking away with 3-4 phones and you end up with a bill for $3000 for phones that were literally taken from under Verizon's nose.