What do I need to know about this offer?
Starting November 17, 2017, for a limited time, customers who purchase an Apple iPhone 7, 7 Plus, 8, or 8 Plus can get a second iPhone 7, 7 Plus, 8, or 8 Plus of equal or lesser value (up to $700) on us via rebate when you:
Activate at least one new line to be used with one of the new devices.
Purchase both smartphones on the same account through our 24-month no-interest Equipment Installment Plan (EIP) with 0% APR.
The new line of service must have one of the new devices purchased on EIP attached to it.
If you cancel wireless service, remaining balance on phone becomes due. For well-qualified customers:
7 32GB: $21.99 down and $22/mo. x 24, full price $549.99.
7 128GB: $121.99 down and $22/mo. x 24, full price $649.99.
7 256GB: $0 down and $25/mo. x 24, full price $600.
7 Plus 32GB: $45.99 down and $26/mo. x 24, full price $669.99.
7 Plus 128GB: $145.99 down and $26/mo. x 24, full price $769.99.
7 Plus 256GB: $145.99 down and $26/mo. x 24, full price $769.99.
8 64GB: $0 down and $29.17/mo. x 24, full price $699.99.
8 256GB: $177.99 down and $28/mo. x 24, full price $849.99.
8 Plus 64GB: $79.99 down and $30/mo. x 24, full price $799.99.
8 Plus 256GB: $229.99 down and $30/mo. x 24, full price $949.99.
Pay the required down payment and any applicable device taxes at time of purchase for each smartphone.
Remain active on an eligible T-Mobile ONE or select Simple Choice with paid unlimited data rate plan, with active EIP and in good standing at least through the receipt of the prepaid MasterCard® card (up to 8 weeks from date you submit your rebate information).

Also note from the FAQ:
If I purchased my devices in Costco, can I still participate in this offer?
Yes. You can participate in this offer if you purchased your devices at Costco by following the redemption steps listed below. Please note that purchases made in Costco will have a different promo code to redeem.

Most importantly, this BOGO offer is offered if you start an Unlimited 55 plan. So, two phone lines that have T-mobile ONE unlimited talk/text/data, with the primary account-holder being over 55 year old, will be $60.

One of the phone lines must be a new line-activation. In this case, my father is the primary account holder and I had his T-mobile number cancelled just a few days ago. So his phone number is a new activation. I am the second phone line, and I had them transfer my number from AT&T.

And, the other thing I wanted to mention is that the BOGO is also for Samsung’s top phones. The Galaxy S8 and S8+, and the Note 8. And just this weekend, they added the Galaxy S8 Active, which was previous only an AT&T exclusive. The local store did not have any S8 Active units on hand, they said they would have it mailed to me, arriving on the 22nd. I ended up getting the Note 8 today, and the S8 Active will be sent to me. Both phones are valued at $820.00.

So, naturally it would have to qualify for their 0% finance plan, you would need to pay $100 down payment for those top tier phones (phones that cost less than $820 have lower down payments) and you also have to pay for the entire taxes for both phone units (a bit of a sting, there).

I believe, in total, I ended up paying about $366 to walk out of there with two activated SIMs, a Note 8, and a S8 Active being mailed to me this week. My phone plan is $60 + $10 because I decided to add ONE plus to my phone line to watch HD video, they were trying to sell me ONE plus on both phone lines for $80. Add another $30 a month for the Note 8, and I believe another $30 for the S8 Active. And after 6 to 8 weeks, when I fill out the rebate forms, I will get a $820 gift card, the full cost of the S8 Active, and I can go to the T-mobile store and pay off one entire phone, and even apply the remaining $100 from the gift card to the other phone.

And I’m thinking of keeping the Note 8, and am thinking of selling the S8 Active. But I don’t know if I should sell it during November/early Dec, or if I have to hold onto it until after I get my gift card. If I sell it, it could practically pay off my Note 8, and therefore just be left with paying for the phone service.

When I did one of their rebates in the late-summer it took almost the full 8 weeks for it to arrive (6+ weeks to get the approval confirmation and another week or so for the prepaid MasterCard to arrive).

If you are going to do this, pay off the phones AFTER you get the approval email (since the rebate is conditioned on EIP) and also put in a request to have them both unlocked. If they ask why, tell them you are going on an international trip and need to be able to use a local SIM for low cost, high speed service. Phones must be used on their service for something like 45 days to be eligible for unlock.