Abstract: The present invention discloses a switching system including a switch exchange coupled to a plurality of telephone lines and a plurality of telephone sets. When the exchange receives an incoming telephone call from the telephone line, it determines idle telephone sets which are able to respond to the incoming telephone call. If all the telephone sets are busy, the exchange holds the incoming telephone call. Then, the exchange detects the number of the held incoming telephone calls and compares the detected number with a predetermined number. If the detected number is more than the predetermined number, the exchange transmits alarm information to a predetermined telephone set to provide notification of the status of the held incoming telephone calls.