Guidance on Connecting a 6-Wire Handset to Intercom in Apartment Block

Buy a complete uniphone matched to the building’s intercom, identify the system first, and wire by function rather than wire color: 1 call, 2 mass, 3 earpiece, 4 microphone, 6 door lock, with terminal 5 bridged to 2 only in 4-wire versions; for a 6-wire installation remove the jumpers [#9729006][#9737557][#10491295][#10828566] If you no longer have the old unit, take photos of a neighbor’s identical handset or the entrance cassette, because the number of wires alone does not determine the intercom type [#9728953][#9729157] If you must identify the conductors yourself, measure relative to terminal 2: the microphone feed on 4 should be about 8–16 V on-hook and 3–6 V off-hook, and if speech direction is wrong, swap terminals 2 and 3 [#10482396][#9737557] To verify the lock line, briefly short the lock wire to mass; if the electric strike opens, that line is correct [#9737557] If everything works except the downstairs side cannot hear you, turn the small blue trimmer on the board to increase microphone gain [#10463753]