How to create a custom Caller UI using Android API

Does anyone know whether Android API libraries supports to create a custom 开发者_开发百科Caller UI? For instance to add a new button on the Caller UI.

The Caller is just another application in Android. Specifically, it is the application named "Phone". For more details about how to create your own dialer though, ask in StackOverflow.com. A.SE is not meant for Android programming.