T-Mobile is running a "Get 4 iPhone 11s on Us" campaign with trade-in of iPhone 7 or better. A couple of my phones are older so am thinking of just buying used(good+ condition) iPhone 7s on Gazelle or Swappa for ~$200 and handing those in for a $700 iPhone 11. This seems too easy and sensible so, before I do that, I just want to check with folks here if I'm I missing something. If it seems too good to be true.....