To look up a number on the Mr. Number app, the user must first download it for an Android. With the app open, users can proceed to look up a number to see what other users of the service have to say about it.
Mr Number keeps a database of numbers from around the world, and users decide whether or not to block them or send them directly to voicemail. Users can also block calls from certain regions and entire area codes. As of 2015, Mr. Number offers 20 free reverse phone lookups, while the app charges the user for subsequent lookups. WhitePages provides the Mr. Number service.