If you are using iOS 9 & above, Truecaller provides a shortcut to lookup a phone number directly from your Phone app, without opening the app. To use it, you must install Truecaller 6.0 or higher and use iOS 9 or later. Then follow these steps to activate it.
- Open your Phone app and go to the ‘Recents' tab.
- Tap the 'info' icon on an unknown number.
- Tap 'Share Contact'.
- Tap 'More' to enable the Search icon.
Now you can just tap the “Search Truecaller” icon to see the result.