Of the to four largest wireless communications carriers in America as of 2015 -- Verizon, Sprint, AT&T and T-mobile -- the only one offering a free iPhone is AT&T. Customers can get a free iPhone 5s from the carrier when they sign new two-year service agreements.
Some websites claim to be giving away free iPhones; however, these sites, such as xpango.com, typically require customers to sign up for a number of other unrelated services that cost money prior to actually receiving the devices, if they ever do. Therefore, the only way to legitimately get a free iPhone is by going through a wireless carrier and signing a two-year service agreement. AT&T wireless is, as of 2015, the only carrier offering such a promotion.