Patent ID: 7023972

Claim:
A communication system in which a plurality of communication terminals, which are connected to a network including a Public Switched Network in a category thereof, mutually communicate through communication data addressed to a common phone number issued by a communication terminal being a management terminal, comprising: a phone number management unit, a message management unit and a bulletin board unit provided in said network, means for registering a predetermined communication terminal so as to correspond to said issued common phone number by sending an identification name of the predetermined communication terminals of said plurality of communication terminals to said phone number management unit in correspondence with said common phone number issued from said management terminal; means for sending a message file from a registered communication terminal using said common phone number to other registered communication terminals via the message management unit when a first mode, in which the message file is to be directly sent to the other communication terminals, is selected, and leaving the message file in said message management unit and notifying the other registered communication terminals of arrival of the message file when a second mode in which any registered communication terminal accesses to said message management unit to receive the message file is selected; means for leaving a message sent by accessing from a registered communication terminal to said common phone number on said bulletin board unit; and means for reading at any time the message file left in said message management unit, in a case where the message file is left in said message management unit, and the message left on said bulletin board unit, in a case where the message is left on the bulletin board unit, from an arbitrary one of the other registered communication terminals.