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Circuit Operation
Subscriber Receives Incoming Call
The following occurs for an incoming call (see
•
FLC-704 detects a ringing signal from the CO, along with Tip-ground
•
FLC-704 signals the FRC-754 to connect Tip-ground and ringing to the PBX
•
PBX goes off-hook and the FRC-754, through the FLC-704, closes the loop between Tip and Ring, the CO
disconnects ringing and establishes an audio path.
Table 8.
Circuit Conditions When a Subscriber Receives an Incoming Call (Ground Start)
Operation
Subscriber Idle
CO seizes loop
CO generates
ringing
Subscriber goes
off-hook
Ring trip
Busy Condition
Ground start busy condition at the RT is a Ring lead negative and a Tip lead positive with loop current flowing.
The same conditions occurs at the CO (see
Table 9.
Operation
Circuit busy
CLASS Features
PG-Flex supports on-hook transmission of analog signals. When Call ID (a CLASS feature) is activated, the CO
generates analog signalling toward the PBX between the first and second bursts of the ringing signal.
Forward Disconnect
The forward-disconnect function releases a called line that was left on hold or an answering set that requires a loop
open to be able to turn off.
8
Table 8
for interactions):
CO Switch
FLC-704 COCU
⇐
Ring - no ground
On-hook
⇒
Tip - ground
No Ringing
⇒
Tip -ground
Ringing
⇐
Ring - no ground
Off-hook
⇒
Tip - ground
No ringing
Table 9
for circuit interactions).
Circuit Conditions for a Busy Condition (Ground Start)
CO Switch
FLC-704 COCU
⇒
Tip - ground
No ringing
⇐
Ring - no ground
Off-hook
January 6, 2003
FRC-754
Subscriber
RTCU
⇐
Ring - no ground
On-hook
⇒
Tip - ground
No Ringing
⇒
Tip -ground
Ringing
⇐
Ring - no ground
Off-hook
⇒
Tip - ground
No ringing
FRL-754
Subscriber
RTCU
⇒
Tip - ground
No ringing
⇐
Ring - no ground
Off-hook
SCP-FRC754-042-03H
FLC-704 List 4B
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