The app's main function is to provide a search feature for Callsigns, allowing users to search for Callsigns and find corresponding information. The information provided includes name, address, and other relevant data. The app's Bandplan feature provides users with access to the frequency allocation chart and details of the authorized modes and power levels for each band.

Callbook ORARI Online is a useful tool for amateur radio enthusiasts, providing them with easy access to Callsign data and Bandplan information. The app's user interface is simple and easy to navigate, making it a great choice for both novice and experienced users.