If you need to call someone back in a hurry, you don't have to redial the number. Don't rummage in your phone app to tap the number in the call log. Instead, use this simple trick to quickly redial the number, whether you have an iPhone or Android.
Open your phone app, and then just tap the call button at the bottom of the display. As long as you have dialed the last number before the call, this number should automatically be entered in the field above. However, that is only half the battle. Make sure you tap the call button again to make your call.