Incoming Caller ID works for some Windows Phone users. If you have a Microsoft Lumia device with Windows Phone 8.1 and the Lumia Cyan update (or more recent) installed on it, you can enable Caller ID in Truecaller.
This feature will not work if you are using a phone manufactured in China, or if you are in the US using Verizon as your carrier. This is due to technical limitations in your phone's firmware that are beyond our control.
If you don’t have a Microsoft Lumia device or you don’t have Windows Phone 8.1 installed on your device, incoming Caller ID does not work due to technical restrictions on the Windows Phone platform.