We use our phone as basic gadget to talk with people and friends.
When you get a missed call from your contacts list, it would be easy to note the name and can call them back according to their priority or so.
But when you dont know who the unkown number then it would make you some unfortable feeling.
Then comes this app which shows the person who called you and their network operator and sometime map locations too.
The layout is so easy to use it shows the unkown number and you can search for the number you want to know.
Feature is a great thing that you can use this as you primary default messenger app.
Using it will prove its use to you.
So you can use it and can find its usefullness.