A bit of good news tonight for those who have the AT&T HTC One. AT&T decided not to use HTC Backup -- which deftly does exactly what it says, backing up your phone via Dropbox -- in its version of the HTC One, which is a shame, because it works quite well. AT&T instead went a different route.
But tonight HTC has released the backup tool as a standalone app. You'll need to sign in with your HTC account, and it'll then back up and restore your phone through Dropbox instead of through Google, which previously was the only option.
Repeat: If you don't have the AT&T HTC One, you don't need this.
And a quick note for those with the developer version (and quite possibly the developer version) of the HTC One: Having an AT&T SIM might let you install the app, but not let you run it, says ol' Jerry.