The telephone switchboard Art. 2904 is used to easily connect the door entry system to the standard telephone system. When a call is made from the external unit, the telephone interface selects a previously programmed number. This may be a unit number or a normal telephone number. It is possible to directly connect a traditional phone or a DECT cordless phone. When the call from the external unit is answered, communication with the visitor is possible. It is then possible to open the main door or activate any other function of your choice. As the interface Art. 2904 is a Simplebus Comelit system, it can be directly connected without using a telephone switchboard. Option of transferring a call (with a delay if required) to an external number. Very easy to program using an analogue phone connected to the switchboard. The Simplebus system can be used to open the door from any phone. For use in large systems. For use with Simplebus 1, 2 and SBC. It should be stressed that the telephone interface is not compatible with the TOP system when main and secondary switchboards are used in the same system, when the intercom function without interface is present and active and when the alarm function is being managed on the system.