A monitoring system for monitoring incoming telephone calls, including telephone calls with different called numbers, the system comprising an electronic processor and an associated database containing caller details with corresponding telephone numbers and details regarding locations and/or people to visit with corresponding telephone numbers, the system being adapted to: detect the originating number of a caller and the called number to which an incoming call was made; to store the time, date and number of the incoming call the originating number of which has been detected and store data representing the number to which the incoming call was made; and to identify the location of the caller/person being visited by the caller corresponding to the detected called number by referring to the associated database, and to identify the identity of the caller corresponding to the originating number by referring to the associated database.