C Spire has simultaneously announced and started selling the HTC One today for $199 on-contract. The Mississippi-based carrier is the eighth-place wireless company in the US, but has still managed to start offering the HTC One before Verizon.
There's nothing unexpected about the HTC One on C-Spire. It's the same phone from other carriers, but it looks like the 32GB silver version is the only option. C Spire has a smallish 4G LTE footprint mostly in Mississippi, Florida, the southern Midwest, and parts of Georgia.