1004 NTCK16 Generic Central Office Trunk cardsLoop start operationLoop start operation is configured in software and is implemented in thecard through software download messages.Idle stateIn the idle state, the ringing detector is connected across the tip and ringwires, providing a high impedance loop toward the Central Office.Call placed by Central OfficeThe Central Office initiates a call by applying ringing between the tip andring wires. If the call is answered, the ringing detector on the trunk cardis switched out and a low resistance dc loop is placed between the tipand ring leads.On trunks configured for battery supervision, the battery detector recordsthe polarity of the tip and ring wires and sends an answer acknowledgesignal to software.Call placed by CS 1000E, CS 1000M, and Meridian 1To initiate a call, the CS 1000E, CS 1000M, and Meridian 1 switches out theringing detector and places a low resistance loop across the tip and ringleads. On trunks configured for battery supervision, the trunk card sends aseize acknowledge signal to software.The system sends digits in the form of Dual Tone Multifrequency (DTMF)tones or pulse digits. When the far-end answers, the Central Office reversespolarity. If the trunk is configured for battery supervision, it sends a polarityreversal message to software.Central Office disconnectThere are two ways the Central Office can disconnect the call:• by applying busy tone toward the CS 1000E, CS 1000M, and Meridian 1.If the trunk card is configured to detect busy tone, it sends a disconnectmessage to software.• by reversing battery. If the trunk card is configured to detect batteryreversal, it sends a disconnect message to software. When the unit onthe trunk card is idled, the trunk card sends a release confirm messageto software.CS 1000E, CS 1000M, and Meridian 1 disconnectThe CS 1000E, CS 1000M, and Meridian 1 disconnects the call by removingthe loop between the tip and ring leads and replacing the ringing detector.Trunks configured for battery supervision send a release confirm messageto software.Nortel Communication Server 1000Circuit Card ReferenceNN43001-311 01.04 StandardRelease 5.0 23 May 2008Copyright © 2003-2008, Nortel Networks.
