PairGain PG-Flex FRC-754 L4, Manual

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363-754-104-01, Revision 01 Product Overview
PG-Flex FRC-754 List 4 June 22, 1998 7
Subscriber Receives Incoming Call. The following occurs for an incoming call (see Table 8 for circuit
interactions):
• FLC-704 detects a ringing signal from the CO, along with Tip-ground
• FLC-704 signal 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
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 for circuit interactions).
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.
Table 8. Circuit Conditions When a Subscriber Receives an Incoming Call (Ground Start)
Operation CO Switch FRC-754 List 4 COCU FRL-754 List 4 RTCU Subscriber
Subscriber Idle
⇐
Ring - no ground
On-hook
⇐
Ring - no ground
On-hook
CO seizes loop Tip - ground
No Ringing
⇒
Tip - ground
No Ringing
⇒
CO generates ringing Tip -ground
Ringing
⇒
Tip -ground
Ringing
⇒
Subscriber goes
off-hook
⇐
Ring - no ground
Off-hook
⇐
Ring - no ground
Off-hook
Ring trip Tip - ground
No ringing
⇒
Tip - ground
No ringing
⇒
Table 9. Circuit Conditions for a Busy Condition (Ground Start)
Operation CO Switch FRC-754 List 4 COCU FRL-754 List 4 RTCU Subscriber
Circuit busy Tip - ground
No ringing
⇒
Tip - ground
No ringing
⇒
⇐
Ring - no ground
Off-hook
⇐
Ring - no ground
Off-hook