need help to use native IN-CALL sreen in 3rd party VOIP app
===

I am developing an VoIP app.

    My app registers to a SIP based back-end server using a User-ID and password.
    Once the registration is successful, the user can make sip calls through this app.
    If the user uses the native phone dialer to dial out a number, My app intercepts the call and places the call through SIP.
    Once the call is intercepted, the native phone dialer goes to background and my app's 'call status' screen is displayed(my app comes to foreground).

My requirements are as follows:

Once the call is intercepted, instead of showing my app's UI, We need to display the native dialer(default phone dialer) 'call status' / 'call progress' screen(like Samsung's Touchwiz for Samsung phones, HTC Sense for HTC phones etc), but the call should go through my app(SIP). Our app should take control over all the functionality of the native dialer 'call status' screen.

Eg: If the user taps the 'Call End' button on the 'Call Status' screen of the native dialer, my app should end the call. Similarly all the controls on the 'Call Status' screen of the native dialer should handover control to my app to take the necessary action.

Please let me know whether it is possible to accomplish this. If it is possible how to implement this?
Please reply ASAP, Thanks in advance.