Truecaller is one of the most widely used contact management app across all smartphone’s, on Android when you receive a call from number which is not there in your contact list then Truecaller will show the name or person who is behind that number.
It has a user base of more than 85 millions users and whenever a user join Truecaller he open his contact list with Name and number to the community which will be made available to other users and then others can also see the name of person behind a number no matter its saved in their contact list or not. Community also flag a number as sales call or so on and you can even block numbers from it.
Till now Live Caller ID which shows name of person when you receive call was not available on Windows Phone due to restriction in API and its functionality was restricted to missed calls only.
But now Microsoft has Truecaller has tied up and Microsoft has opened up its API specially for Truecaller which lets Windows Phone user to identify the person behind a number in real time or if its a spam call then reject it.
This Live Caller ID functionality will only work with Windows Phone 8.1 Update, you can download Truecaller from marketplace