How to mimic a incoming call?

Hi All.

Can you please help me try to generate a fake incoming call (even w/o any n/w)

Pl try to answer the following questions to the above effect-

1. Is there a default Activity/View/ViewGroup which is used for incoming calls?
If yes what is its name (need to override).
2. Is there a service to be called for the default ringtone to be used?
If yes, its whereabouts please.
3. Any other detail which you deem necessary for me to know, please share.

(If this isn't the right category to post this, please lemme kno the right one...will post there)

Awaiting quick reply (deadline to meet).

Thanks n regards,
Prithvi.