Device for determination and display of the cheapest telephone call cost has three disks that rotate relative to each other so that by selecting a time and other factors an indicator arrow shows the cheapest service provider

摘要

Device has middle disk (1) and two outer disks (2,3) linked at their mid-points so that the disks can rotate relative to each other. The disks have colored segments arranged on them with a 24 hour clock, distance zones, tariffs, service providers. The user rotates one of the two outer disks to position an arrow on a time and in a circular sector viewing window reads of the cheapest price.