| 摘要 |
PURPOSE:To send a message waiting signal to an indicator MWL in a private branch exchange accomodated in a hotel or the like by sending said signal through an extension circuit LC having a calling signal sending function by the key operation KEY of a frontsman. CONSTITUTION:Plural output phases (PH0-PH3, 0.5sec: ON, 2.5sec: OFF) are provided for an intermittent ground circuit IG in a calling signal sending circuit RNG and one or plural phases (PH1, PH3) are assigned to message waiting signal sending. A message waiting signal is sent by a calling signal sending means of an extension circuit corresponding to the operation of a key KEY for message waiting indication through a switching circuit MWC for intermettently switching the sending line of a calling signal from a calling signal source SIG to a message waiting signal power source (+150V) side in accordance with the intermittent ground outputs of the assigned phases. |
