If your television is connected via equipment other than a mini box, such as a Cox HD receiver or a Cox-provided CableCARD together with a CableCARD compatible retail device (and a Cox-provided Digital Tuning Adaptor for certain channels), programming is available in high definition only at the HD Channel position - typically the four-digit number above 1000.
available in high definition only at the HD Channel position
This is a recent change so Cox probably hasn't updated their web page.
These "positions" are called Virtual Channel numbers and are sometimes remapped. Virtual Channels are what you press on the remote control and not the actually frequency of a transmission.
The "big" networks insist lower Virtual assignments so their programming isn't buried deep within the program guide. I remember when Fox first launched and there was lots of contention for lower channels.
I think providers screwed up back during our transition from analog to digital TV. If Digital TV was to be the future, why didn't the providers originally map (assign) all HD channels to the 2- or 3-digit equivalent and make SD channels 4-digit. "Oh...we didn't want to confuse everyone?" It would have been better to confuse us then rather than now.