Abstract: A semi-automatic or a fully automatic intercom system. These intercom systems are hardwired intercom systems which cannot be used with telephone lines. The semi-automatic intercom system can be used with any kind of lobby panel including a lobby panel equipped with a keypad and an electronics board. The fully automatic intercom system according to the invention can be used only with a lobby panel equipped with a keypad and an electronics board. The fully automatic system can automatically disconnect a shorted out apartment unit from the system and restore the building to service immediately.

Abstract: A self-correcting intercom system with circuitry to detect faults within the circuitry and phone lines and reset the system to a pre-fault condition on the occurrence of a fault. The intercom system has an alarm system with a line control unit and a timer to reset the intercom system to a standby condition. A set up control unit includes all of the codes and signals to reset the other components of the intercom system upon activation of the set up control by the timer or the line control unit. A timer activates the set up control unit when a user initiates a call from an entrance vestibule panel to an apartment unit and no connection has been made within a certain time period. A line control unit activates the set up control when a connection is made, but a line fault such as a short circuit occurs disrupts normal communication. The system consumes electrical power only when needed.