in my app I should do some action when a call comes but not answered by the user.
I have searched in the android.telephony and the NotificationManager<
I suppose you have content providers to access call logs.
http://www.anddev.org/video-tut_-_querying_and_displaying_the_calllog-t169.html
http://www.devx.com/wireless/Article/41133
If this code works you just need to run this query at the right time. I mean check some samples that can notify you when you get a call in your device
http://groups.google.com/group/android-developers/browse_thread/thread/d97a759a3708cbe3
Once you get this notification put a timer or use some built in Intents to find that the phone is back to normal state and access the call logs...
Possible duplicate
broadcast receiver for missed call in android
Show Toast on Missed Call in android application