While it appears on nearly all Android devices, the Phone app can vary quite a lot between different devices. This is mainly due to extensive customization by manufacturers. Despite this the Phone app has a number of settings that can be commonly found.
The settings for the Phone app can usually be found under the overflow menu (three dots icon) in the top right from the main screens of the app.
The Display options allow for changing the sort order of contacts, and whether names are to be shown with the first name or surname first.
Sounds and vibration
This setting allows for changing Android's incoming call ringtone, and mirrors the Phone ringtone setting in the Android Settings menu under Sound.
Enables or disables the playback of dialpad tones when dialling using the number pad, either to enter a phone number or while in a call.
Enabling this plays audible tones through your phone's speaker, but this setting does not alter what is sent over the phone connection.
Quick responses are short, predefined text messages that can be sent back to the caller with just a couple of button presses when receiving a call if you are unable to pick up the call. You can define your own messages here. Messages may be chosen which can politely tell the caller that you are unable to receive their call and whether you will call them back.
Most of the time your device will have a fixed number of slots in which you can enter your predefined messages. From the list of messages, tap the one you wish to edit and you will be able to alter the message in that slot.