https://www.cnet.com/news/black-friday-2018-galaxy-deals-free-galaxy-s9-plus-600-note-9-300-gift-card-sales/

Verizon's promotions are pretty straightforward. Buy a Galaxy S9 and Verizon will give you a second S9 for free when you activate an additional line of service (you're still paying for the service). Or, if you're not wooed by this BOGO, you could knock $800 off the cost of the pricier, larger Galaxy Note 9 or Galaxy S9 Plus, also when you open a new line of service. Either way, you'll see your discount in the form of bill credits spread over the next 24 months.

T-Mobile's Black Friday deal starts Nov. 16, and... it's a little complicated, so bear with me. You can get a phone either for free (chosen among select models), or you get up to $750 off the phone's full price. That's if you trade in an older phone and add an additional line of service to your plan. So, if you already have one phone line, this deal applies if you add a second line. If you pay for two phone lines, it works when you add a third.