TrueCaller helps you identify the person who is making that phone call to your number. When a call is received from an unknown number that does not exist in your phone’s address book, TrueCaller queries its global telephone directory to identify the personal behind that unknown number.

On first run, you need to select your country and your preferred language. TrueCaller will then ask for your permission to enable extended search – if you say yes, the app uploads your entire phonebook contacts to TrueCaller servers to include inside their global search database. You can skip the option if you care about privacy and do not want to share your contacts with TrueCaller.

You can also connect your Facebook, Twitter and Linkedin account with Truecaller – it syncs updates from your social networks (status, photos, birthdays) with your phonebook.

On incoming calls, Truecaller searches its database in real-time for matching numbers and displays a pop up box with details regarding the number on caller screen. Once the call is over, it displays a dialog box with details regarding the number along with the option to save them to your phonebook. You can also mark the number as spam from the dialogue box.

It also works with SMS – a popup box comes up when an SMS arrives. You can setup the duration of the popup box as well as its position. You also have the option to use the app as a call blocker – create a blacklist by adding numbers manually or by selecting numbers from your call log.

Keep in mind that Truecaller requires connection to Internet to access its database for search. If you are using 2G, Truecaller will search for details regarding the number when the call is disconnected and Internet connectivity is resumed.

You can also search for details regarding a particular number by searching for it manually in the app.

Although the app does not display advertisements in the main app window, strip ads are displayed at the bottom of the after call dialogue box.