HP FlexNetwork MSR Series Configuration Manual page 85

Table 5 Line signaling bit description
Bit Description
Identifies working state of device at the
a originating side and indicates state of the calling
f
party line.
Indicates fault state from the originating side to
b
f
the terminating side.
Indicates state of the called party line (on-hook
a
b
or off-hook).
Indicates state of device at the terminating side
b
b
(idle or seized).
Table 6 State code of line signaling
State of the circuit
Idle
Seized
Seizure-ack
Answer
Clear-back
Clear-forward
Blocked
Unblocked
The following are typical R2 digital line signaling interaction procedures:
1. Call establishment.
When the circuit is idle, the originating side sends a forward seizure signal to the terminating
side. The terminating side then sends back a seizure acknowledgement signal after it
recognizes the seizure signal. At this time, the circuits of the both sides are seized, and they
start interregister signaling exchange. When the called party picks up the phone, the
terminating side sends a backward answer signal. After the originating side recognizes the
received signal, it establishes the call.
Figure 19 R2 digital line signaling – call establishment
Vale = 0
Off-hook, seized
Normal
Off-hook by called
party
Idle
Signaling code
Forward
a b
f f
1 0
0 0
0 0
0 0
0 0
0 0
1 0
1 0
72
Value = 1
On-hook (idle)
Faulty
On-hook by called party
Seized or blocked
Backward
a b
b b
1 0
1 0
1 1
0 1
1 1
0/1 1
1 1
1 0