DEFINITY Enterprise Communications Server Release 7
Maintenance for R7r
555-230-126
Issue 4
June 1999
Maintenance Object Repair Procedures
9-428CO-TRK (Analog CO Trunk)
9
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
