C-18 SmartSwitch 1800 4.0 User Guide, Rev 01E&M Type IIIdle Condition: The "E" lead is biased by the PBX at -48 Vdc. The "M" lead is biasedat -48 Vdc by the attached device (SmartSwitch 1800).PBX Initiated Call: The PBX grounds the "M" lead, signaling to the attached devicethat it wants a connection. The attached device grounds the "E" lead, signaling theresponse.Attached Device-Initiated Call: The attached device grounds the "E" lead, signalingto the PBX that it wants a connection. The PBX grounds the "M" lead, signaling theresponse.PBX-Initiated Disconnect: The PBX initiates disconnection by opening the "M"lead. The "M" lead is pulled to -48 Vdc, as biased by the attached device. In response,the attached device opens the "E" lead, which is pulled to -48 Vdc, as biased by thePBX.Attached Device-Initiated Disconnect: The attached device initiates the disconnectby opening the "E" lead. The "E" lead is pulled to -48 Vdc as biased by the PBX. Inresponse, the PBX opens the "M" lead, which is pulled to -48 Vdc, as biased by theattached device.E&M Type VIdle Condition: The "E" lead is biased by the PBX at -48 Vdc. The "M" lead is biasedat -48 Vdc by the attached device (SmartSwitch 1800).PBX-Initiated Call: The PBX grounds the "M" lead, signaling to the attached devicethat it wants a connection. The attached device grounds the "E" lead, signaling theresponse.Attached Device-Initiated Call: The attached device grounds the "E" lead, signalingto the PBX that it wants a connection. The PBX grounds the "M" lead, signaling theresponse.PBX-Initiated Disconnect: The PBX initiates disconnection by opening the "M"lead. The "M" lead is pulled to -48 Vdc, as biased by the attached device. In response,the attached device opens the "E" lead, which is pulled to -48 Vdc, as biased by thePBX.Attached Device-Initiated Disconnect: The attached device initiates the disconnectby opening the "E" lead. The "E" lead is pulled to -48 Vdc as biased by the PBX. Inresponse, the PBX opens the "M" lead, which is pulled to -48 Vdc, as biased by theattached device.
