NT8D14 Universal Trunk card Page 583 of 906Circuit Card Description and InstallationFigure 122Ground start call connection sequence – outgoing call to CO/FX/WATSAStateIdleIdleB ringsTrunk seizureDial tone from COB goes on hookIdleA goes on hookRemarksSignal/directionNear endSystemBFar endCOTip open/batteryon ringTip open/battery on ringRingbackTip open/battery on ringHigh-resistanceloopGround on ringWhen the CO recognizes seizure, it grounds the tipand supplies dial tone.When terminal B answers, ringing is tripped and COcuts terminal B through to trunk. Some COs mayreverse battery and ground on tip and ring whenterminal B answers or for toll denial.Upon receipt of the first pulse/tone, the CO removesdial tone. When outpulsing is complete, terminal B isrung (if idle) and the proper audible indication isreturned to local end.If far end disconnects first, CO removes ground fromtip. If battery and ground were reversed when callwas established, battery is removed from tip andrestored to ring.Near end detects drop in loop current and opens loop.Digits are outpulsed in the form of a series of looppulses or DTMF tones.2-way voiceconnectionGround on tip/battery on ring,dial toneLow-resistance loopHigh-resistance loopHigh-resistance loopAddress signalingDetection of the ground on tip is signaled to the CEvia the data input bus. The CE then sends a signal viathe data output bus to place a low-resistance loopacross the tip and ring and remove ground from ring.Terminal A dials trunk access code. CE sends amessage via the data output bus to ground the ring.If near end disconnects first, it opens the loop.CO detects drop in loop current and removes groundfrom tip. If battery and ground were reversed whencall was established, battery is removed from tip andrestored to ring. 553-AAA1136
