Setting Speed Dial
Open the Contacts app, then tap the Menu icon
(at the upper-right corner of the screen).Tap Speed dial.
Tap the speed dial number to assign.
Tap the Contact entry.
Setting Speed Dial for contact entries with multiple saved numbers
The Speed dial icon 
in the contact entry allows you
to set speed dials for selected phone numbers.
From the contact entry (either when creating it or while editing it later), tap the Speed dial icon
to the right of the phone number
you want to set with a speed dial.Tap the speed dial number to assign to it.
Tap SAVE (at the bottom of the screen).