HTC One Remix - Manual (Page 121)

If you have multiple missed calls, tap the missed calls notification to open
the Call History tab.
Speed dial
Use Speed dial to call a phone number with a single tap.
1. Open the Phone app.
2. Tap > Speed dial > . You can also press and hold an unassigned
key on the dialpad, and then tap Yes.
3. Select a contact from the list.
4. On the Speed dial screen, choose the phone number of the contact
to use, and a speed dial key to assign.
5. Tap Save.
To use Speed dial, press and hold the speed dial number you want to call.
Phone calls 121