Regional time difference in a telephone exchange

摘要

A telephone exchange 10 is connected to a communication terminal installed in a predetermined region through a network. The telephone exchange includes: a reference time acquisition unit 15 that acquires a reference time; a storage unit 14 that stores time difference information 14a concerning a time difference between a local standard time of the standard time in the predetermined region and the reference time acquired by the reference time acquisition unit; a local time calculation unit 16 that calculates a local time of the time in the predetermined region based on the reference time obtained by the reference time acquisition unit and the time difference information stored in the storage unit; and a communication unit 12 that transmits the local time calculated by the local time calculation unit to the communication terminal suitable for Internet Protocol (IP) based exchanges (IP-PBX).