Originally Posted by
HockeyCoachBen
This is precisely the reason why despite being a T-Mobile customer, I always buy my iPhone directly from the Apple Store and chose the 'worldliest model' (model/version which supports the most frequencies/LTE bands).
The problem is you can't pre-order online and have your phone delivered on launch day this way. I'm a T-Mobile customer as well and bought my iPhone 7 Plus through Apple when the pre-orders went live. You can't place an online order for a Sprint/Verizon/AT&T phone without being a customer of that carrier.
You'd basically have to wait in the crazy line on launch day and buy a phone at full retail, and that's assuming they'd have the color/capacity of your preference.