Short story is they get a comission from VZW when they do a deal, they basically pass along some savings. Say a phone is $500 retail and they get $600 each sale, so they give it free and pocket $100.
If you look at the bottom of their site and Walmart, Costco, sams, Target, they are all processed via the same company, I forget the name. They are basically wirefly, as the address are the same for both.
Just look at the terms. If you cancel service with 3 or 6 months you get charged by them in addition to VZW. But if you stay with VZW then no problems
Sent from someplace, and with something that you need not worry about.