Handle external interrupts while switching activities in an App

I Have developed an application which contains many activity.

I have noticed an issue while one activity starts another activity and meanwhile if we press camera button or get a call my application hangs and never recovers even after ending the call or closing the camera.

Basically what I want to know is how to handle external interrupts(alarms, calls, camera) so that my app resumes from where it had stopped.

I am replicating this issues on emulator as well as on LG Device.Can anyone give me some idea to how to handle onpause and onrsu开发者_如何学编程me function call in this case.

Thanks