Samsung Ubigate iBG2016 Configuration Manual page 589

Ground Start
Ground Start signaling was originally developed to aid in resolving Glare.
In Loop Start the only way to indicate an inbound call from the network is to
Ring the phone. During a full 6-second ringing cycle there is a 4-second
period when the phone is not physically ringing. So how do you know whether
a PBX is trying to answer an inbound call or if it is trying to initiate a new
call? Ground Start eliminates this problem by adding an additional state
(Tip Closed) which tells the FXO circuit that there is an inbound call in
progress, even during the 'quiet' ringing cycle.
For outbound calls, the PBX(or FXO interface) must first seize the line by
applying ground to the Ring lead of the Tip/Ring pair(Ring Ground).
The CO(or FXS interface) now knows that the FXO is trying to make an
outbound call, and it will not terminate inbound calls on that circuit.
Digital Loop-Start signaling
In case of Loop-start signaling, it works according to the following state table.
Incoming Call
State
Idle
Seizured
Outgoing Call
State
Idle
Seizing
Seizure Ack.
Seizured
© SAMSUNG Electronics Co., Ltd.
Sent
a[f] b[f]
0 1
0 1
Sent
a[f] b[f]
0 1
0 0
0 0
0 1
Ubigate iBG2016 Configuration Guide/Ed.00
Received
a[b]
0
1
Received
a[b]
0
0
1
1
b[b]
1
1
b[b]
1
1
1
1
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