A telephone call alerting system is applied to a telephone communication system accommodating a line to which a telephone terminal is connected, a plurality of telephone numbers being assigned to the line. The telephone call alerting system includes an output unit for outputting information indicating a telephone number of a call when the call is received by the telephone terminal, a plurality of informing units for outputting an alert indicating that a call has been received by the telephone terminal, each of the plurality of informing units corresponding to one of the plurality of telephone numbers, a memory unit for storing a table indicating a relationship between the plurality of telephone numbers and the plurality of informing units, an identification unit, when the call is received by the telephone terminal, for identifying one of the plurality of informing units corresponding to the telephone number indicated by the information output by the output means, with reference to the table, and a control unit, when the call is received by said telephone terminal, for supplying an instruction of outputting the alert to the one of the plurality of informing units identified by the identification means, so that the one of the plurality of informing units outputs the alert.