CONCENTRATOR

PROBLEM TO BE SOLVED: To provide a concentrator in which internet telephone can be effected using a standard telephone without requiring to introduce a unit for connecting a standard telephone with a computer or to call a provider. SOLUTION: The concentrator 101 comprises one or a plurality of terminal interfaces 104, 105, 106 and 107 being connected with a terminal, a public line interface 103 for connection with internet through a public line, a communication function section 102 for controlling a voice signal or I/O of IP packet at the terminal interfaces 104, 105, 106 and 107 and the public line interface 103. The concentrator 101 further comprises a section 108 for mutually converting an IP packet and a voice signal, a memory 109 for storing an IP address, and an internet telephone section 110 having the function of internet telephone.