| 摘要 |
PURPOSE:To make it possible to test a transmission line including modems by making a continuity test between modems in a packet network by providing a switch, which makes connection among testing modems, several internetwork circuits and modems, to a barrier office. CONSTITUTION:In barrier office 101, continuity-testing modem 102 is connected to a tested circuit via connection switch 103 to make modem 102 start carrier transmission, thereby sending a carrier to an interline circuit. Among modems 201-20n on a packet network side, a modem corresponding to a set circuit detects the carrier and informs packet switchboard 210 of that. On receiving the reception of the carrier, switchboard 210 lets a corresponding modem on the packet side start the transmission of a carrier on the opposite side to send the opposite carrier to a telephone side. This carrier is detected by modem 102 to inform the barrier office of that, thereby completing the continuity test. |
