If the app is enabled it looks at a incoming phone number andcompares it to a pre-set number(s). If these numbers are the samethe phone will automatically answer the call. You can also enableand disable speakerphone.
This app is activated by System intents. So you can leave theapp and let it run in the background. But because of the use of theSystem intents it does not take up any battery and it is onlyactivated by the system when a incoming call is detected.
***
Example 1
Leave a phone with this app on a location you want to eavesdrop andcall it with an other phone (does not have to be android). Yourandroid phone with this app will atomically answer your call andyou can listen to what is happening on the eavesdrop location.
Example 2
Leave a phone with this app on a location with a person who is notable to pick up the phone (children, elderly, disabled) call andcommunicate with this person.
Example3
use your imagination...
***