Avaya S8700 - Page 1175

CO-TRK (Analog CO Trunk)
Issue 1 May 2002
8-453555-233-143
Loop Start Operation
Idle State: Tip = ground, Ring = CO Battery Outgoing Call:
1. PBX Off-Hook (Seize message): Closes the Tip-Ring Loop
CO response: DC loop current + Dial tone
2. PBX On-Hook (Drop message): Open Tip-Ring loop, no loop current
CO response: CO goes to idle state (see Note)
Incoming Call:
1. CO Applies Ringing Voltage
PBX response: Detect ringing current
2. PBX Off-Hook (Answer message): Close loop
CO response: Trip ringing, provide loop current
3. PBX On-Hook (Drop message): Open Tip-Ring loop, no loop current
CO response: CO goes to idle state (see Note)
NOTE:
CO does not normally provide an On-Hook (Disconnect) signal.
Exceptions to this rule include Netherlands loop start and UK
loop-calling guarded-clearing.
Ground Start Operation
Idle state: Tip = open, Ring = CO Battery Outgoing Call:
1. PBX Off-Hook (Seize message): Places ground on Ring
CO response: Places ground on Tip
PBX response: Close the loop
CO response: Provide loop current
PBX response: Dial out digits
2. PBX On-Hook first (Drop message): Open the Tip-Ring Loop, no loop
current
CO response: Open circuit on Tip
3. CO On-Hook first (Disconnect): Open circuit on Tip, no loop current
PBX response: Open Tip-Ring loop