| 摘要 |
PROBLEM TO BE SOLVED: To provide a telephone system which overcome reduction in performance of an IP telephone due to the effect that, when a plurality of IP telephones respond to a call-out or call-in all at once, traffics of a LAN transmission line abruptly increase and a timing of transmitting control information to the LAN transmission line delays, and an overhead of checking presence or absence of a collision increases. SOLUTION: A button telephone device 10 and a plurality of IP telephones 20A to 20N are connected via a LAN transmission line 30. Control information 31 from the button telephone device 10 to the IP telephones 20A to 20N is stored in a transmission cycle storing part 12 of the button telephone device 10 and is transmitted at a designated transmission cycle (T1). Further, each IP telephone 20 transmits control information 71 to the button telephone device 10 after a loop time (T2) stored and designated by a loop time storing part 13 of the button telephone device 10 elapses.
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