Services Supported By Diod Trunks; Loop Start Operation - Avaya G250 Maintenance Manual

Services Supported by DIOD Trunks

Direct inward and outward dial (DIOD) trunks are 2-wire analog lines to the CO which support
the following services:
Both incoming and outgoing CO calls
●
DID trunk
●
DID trunk and 1-way outgoing DIOD
●
MM711 trunk media modules provide eight ports for loop-start CO trunks.

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).
Direct Inward Dialing (DID)
1. CO Applies Ringing Voltage.
a. PBX Response: Detect ringing current and close loop.
b. CO Response: Send DTMF digits.
c. PBX Response: Acknowledge of Number dialed and open loop.
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.
Note:
DIOD-TRK (DIOD Trunk)
Issue 1.1 June 2005 161