How to change existing UI screen to my own UI screen?

I am writing a code 开发者_如何学Gofor Dialing calls. I am using my own UI (i.e display screen), when i touch a button on the screen for dial button, it is dialing but the existing dialing screen is displayed. I want my own screen to be displayed where i use a button to end a call.Can any one tell me how can i get my own screen displayed instead of the existing screen.I have used the following code:

Uri parsedPhoneNumber = Uri.parse("tel:" + number);

Intent i = new Intent(Intent.ACTION_CALL, parsedPhoneNumber);
startActivity(i);

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private void call() {
try {
    Intent callIntent = new Intent(Intent.ACTION_CALL);
    callIntent.setData(Uri.parse("tel:123456789"));
    startActivity(callIntent);
} catch (ActivityNotFoundException e) {
    Log.e("helloandroid dialing example", "Call failed", e);
}
}