Nortel Circuit Card, Installation Manual, Page: 55 / 908

Overview Page 55 of 906
Circuit Card Description and Installation
Ground Start Restrictions
If the lineside T1 card is used in ground start mode, certain restrictions should
be considered. Because the system treats the lineside T1 card as a standard
loop start analog line card, the ground start operation of the lineside T1 card
has operational limitations compared to typical ground start interface
equipment relating to
start of dialing, distant end disconnect and glare
potential .
• Terminal equipment goes off-hook by simulating ground on tip
lead and ringing on ring lead. 0 0/1 1 1
Outgoing Calls (from terminal equipment):
• Idle 1 1 0 1
• Terminal equipment goes off-hook. 1 1 0 0
• The lineside T1 simulates grounding its tip lead 0 1 0 0
• Terminal equipment opens ring ground and closes loop 0 1 1 1
Call Disconnect from far end:
• Steady state (call in progress) 0 1 1 1
• The lineside T1 ungrounds tip 1 1 1 1
• Terminal equipment opens loop current 1 1 0 1
Call disconnect from terminal equipment:
• Steady state (call in progress) 0 1 1 1
• Terminal equipment goes open loop current 0 1 0 1
• Lineside T1 card opens tip ground 1 1 0 1
Table 5
Ground Start Call Processing A/B Bit Settings (Part 2 of 2)
State
Transmit Receive
A B A B