CU100 is a user-friendly Customer Interface Unit (CIU) applicable to conventional and smart prepayment meters. CU100 can communicate with prepaid meters through wired (PLC/M-Bus) or Wireless (RF-LoRa) communication options, providing a reliable and free interface to end-user customers, which makes them possible to access to different functions and data, e.g. credit charging, credit balance alarming, history of tokens, real-time energy and demand values, friendly mode, emergency mode etc. CU100 is equipped with a large LCD, and big keypad buttons, adjustable buzzer and the backlight for both LCD and keypad.