This data is generally captured through a feedback form or in some cases from your contacts list without your notice.
This piece of information is collected collaboratively from different users who already stored a particular number on their contacts list, after that using the machine learning approach the data is filtered and stored with the best possible yet effective combination to display further when required. This data is generally captured using the signup form, where the original user has to fill in all the details while registering on the app for the first time. This data is usually collected and stored inside the central server according to the user-provided information without any major changes when new users signup for the first time to use their services. The information provided by the TrueCaller app is mostly collected from these two sources:
Then the details of the caller are displayed with an on-screen hovercard for both of the end-users to introduce who they are calling to and or getting the call from. If the application is already installed on a mobile device and when there is a calling session yet to start, the app immediately captures and auto-verify the number along with the caller details by communicating with its own server.