AT&T, T-Mobile, and Verizon are offering $700 back in billing credits over 24-months when you buy two iPhone XS or XS Max Smartphones and open a new line of service for a limited time. This is not an offer that is enticing for most people but if you are the select few that are looking to buy two of the newest iPhones and are also looking to open a new line of services and don’t mind sticking around for 24 months, this could save you a decent chunk of money.