U77 Intercom systeem

The U77 intercom system was available in several variants. There was the U77 2L1 (2 lines – 1 telephone), 2L2 (2 lines – 2 telephones), 4L1 (4 lines – 1 telephone), 1L5 (1 line – 5 handsets). Each of these was connected to a specific handset (dial or keypad); the 2L2 model was also available with a memory function (black key). The connection always ran from the relay to handset 1, from handset 1 to handset 2, and so on. The handsets were never connected individually to the relay.