CO-TRK (Analog CO Trunk)

Table 61. CO-TRK (Analog CO Trunk)

MO Name (in Alarm Log)	Alarm Level	Initial Command to Run*	Full Name of MO
CO-TRK	MAJOR**	test port GGGVSpp l	Analog CO Trunk
CO-TRK	MINOR	test port GGGVSpp l	Analog CO Trunk
CO-TRK	WARNING	test port GGGVSpp l	Analog CO Trunk
Note: For Avaya G700 systems you must consult local records for the location and designation of the equipment rack where the G700 is mounted.
**A MAJOR alarm on a trunk indicates that alarms on these trunks are not downgraded by the set options command and that at least 75% of the trunks in this trunk group are alarmed.

Analog CO trunks are 2-wire analog lines to the CO which support both incoming and outgoing calls. CO trunk Media Modules have eight ports.

The following sequences show the interactions between the switch and the CO during call setup for both loop-start and ground-start trunks.

Loop Start Operation

Idle State:

Tip = ground, Ring = CO Battery

Outgoing Call:

1. PBX Off-Hook (Seize Message): Closes the Tip-Ring Loop
2. CO Response: DC loop current + Dial tone
3. PBX On-Hook (Drop Message): Open Tip-Ring loop, no loop current
4. CO Response: CO goes to idle state (see Note)

Incoming Call:

1. CO Applies Ringing Voltage
1. PBX Response: Detect ringing current
2. PBX Off-Hook (Answer Message): Close Loop
1. CO Response: Trip ringing, provide loop current
3. PBX On-Hook (Drop Message): Open Tip-Ring Loop, no Loop Current
1. CO Response: CO goes to idle state (see Note)

Ground Start Operation

Idle state:

Tip = open, Ring = CO Battery

Outgoing Call:

1. PBX Off-Hook (Seize Message): Places ground on Ring
1. CO Response: Places ground on Tip
2. PBX Response: Close the loop
3. CO Response: Provide loop current
4. PBX response: Dial out digits
2. PBX On-Hook first (Drop Message): Open the Tip-Ring Loop, no loop current
1. CO Response: Open circuit on Tip
3. CO On-Hook first (Disconnect): Open circuit on Tip, no loop current
1. PBX Response: Open Tip-Ring loop

Incoming Call:

1. CO Off-Hook (Seizure): CO applies ground on Tip and applies ringing voltage
1. PBX Response: Make trunk busy for outgoing calls
2. CO Ringing: CO applies ringing voltage
1. PBX Response: Detect ringing, ring destination
3. PBX Off-Hook (Answer Message): Close loop
1. CO Response: Trip ringing, provide loop current
4. PBX On-Hook first (Drop Message): Open the Tip-Ring Loop, no loop current
1. CO Response: Open circuit on Tip
5. CO On-Hook first (Disconnect): Open circuit on Tip, no loop current