java/com/android/incallui/incall/impl/res/color/incall_button_icon.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
  <item android:color="#FF01579B" android:state_checked="true"/>
  <item android:color="#FFFFFFFF"/>
</selector>