Within GPO/BT This was known as the Coin Telephone 23 or CT23 see also www.britishtelephones.com/ct23.htm

www.britishtelephones.com/ct23.htm

Coin Telephone 23A and 23C compared

The 23A has a * and # and R extra buttons

The 23c had a tariff setting button that can be pressed with the coin collecting box open

The 23A has a separate tariff eprom

The 23A has spade line connections on the main PCB where as the 23C has a BT plug and socket

The 23A has more metal inside, where as the 23C has plastic parts

The 23C does not have a PCB on the coin route, the ribbon cable is wired direct to the Elecro- Magents / opto sensors

RAA           Landis & Gyr (formerly Aeronautical & General)