ALARM INTERNAL COMMUNICATION DEVICE Russian patent published in 1996 - IPC

FIELD: telephone sets. SUBSTANCE: device has N user units 1.1-1.N, where N is equal to or greater than one. Each user unit has speaking hand set 2, loud speaker 3, calling unit 4, power supply unit 5, two light indicators 6, 7, two button switches 8, 9, call signal indicator 10, user selection unit 11, which has N switches 12.1-12.N, decoupling capacitor 13, loud speaker 14, two diodes 15, 17, clamp control electromagnet 16, resistor 18, lock clamp 19. EFFECT: increased functional capabilities, increased reliability, simplified design.