If you want to make a call by tapping one key, you need to assign the contact to a speed dialing key. But first you need to save the contact in the address book.
Assign contact to speed dialing key
Return to the home screen
Tap the menu icon.
Tap Speed dial.
Tap "+ Add contact" next to the required speed dialing key.
Tap the required contact.
Tap the Home key to return to the home screen.
*Please refer to the Samsung website for more information or further support.*