It should come as no surprise to long-time OnePlus users, but the company's newest phone, the OnePlus 6, doesn't work on the largest U.S. carrier, Verizon, nor the fourth largest, Sprint. That's despite technically supporting most, but not all, of the wireless bands a phone typically needs to run on those networks.
Given that no OnePlus phone — nor most "unlocked for the world" phones — have supported Verizon and Sprint in the past, the realization isn't particularly shocking, but a closer look at the OnePlus 6's spec sheet would lead one to believe that it would be possible for the phone to connect to those networks.
If you're a Sprint or Verizon customer, stay away from the OnePlus 6.
The North American version of the OnePlus 6 supports CDMA bands BC0 and BC1, legacy 3G signals that Verizon and Sprint both still use for phone calls, texts, and fallback data in areas without LTE. Moreover, the phone supports all but one of Verizon's common LTE bands — 2, 4, and 5 — with band 13 being the single outlier. Unfortunately, Verizon relies heavily on band 13, which encompasses the long-traveling 700MHz signals prized in rural deployments — which precludes Verizon from supporting the phone on its network. Indeed, even if the OnePlus 6 supported band 13, it would still need to be approved by Verizon for use on its network, going through an extensive certification process. OnePlus has never implied it would seek such a certification, and it looks like it's still off the table now.
On the Sprint side of things, the OnePlus 6 supports bands 25 and 26, but not 41, which is where the majority of Sprint's deployments lie. Sprint also requires manufacturers to certify their phones for its network, but the company is considerably more opaque about the process. In other words, the OnePlus 6 never had a chance with Sprint.
Such limitations also preclude the OnePlus 6 from working on Google's popular Project Fi MVNO, and any other wholesalers powered by Verizon or Sprint. On the flipside, the phone works out of the box with AT&T and T-Mobile SIM cards, and even supports VoLTE and VoWiFi on the latter.
You know what phone does work on Verizon, though? The Pixel 2.