Android app

I want to create an app or install existing app. I want to connect my android 2.1 mobile to a door bell. I will keep my phone above door connected with my door bell. When any one press the bell my phone cam and audio speaker will get activated and and I can communicate the guest from inside when I will talk from Inside phone my outside phone will reply and I can see the guest from inside phone. I can connect the both phones in same wifi network.