Sprint HTC One

If you've got an HTC One on Sprint, be on the lookout for a little update starting today. Sprint's pushing software version 1.31.651.2 that has an "HD Voice enhancement" and fixes things so Sprint's ringtones will show up in the ringtones list. HD Voice, of course, requires you to be speaking to someone else who has an HD Voice-capable phone. 

Keep an eye out for it any time now.

Source: Sprint; via HTC One (Sprint) forums