Verilink PRISM 3030 (34-00208.L) Product Manual - Manual (Page 99)

Ground Start Signalling (MEGACOM) 89
Ground Start
Signalling
(MEGACOM)
Idle
State
The FXS application module has the tip open and
−
48 VDC on the ring towards
the CPE. The CPE has tip and ring open toward the FXS. The FXS transmits both
A and B signalling bits = 0 toward the network, receives an A bit = 0, and ignores
the B bit from the network.
Call Originated
from Network
The FXS application module receives an A bit = 1 and the B bit is ignored from
the network. The change of state of the A bit causes the FXS application module
to do the following.
✦ Set the B Transmit signalling bit to a 1 for approximately 200 ms and then returns
it to a 0.
✦ Send ring voltage with ring cadence toward the CPE.
✦ Send ring back tone towards the network, coincident with the ring cycle.
CPE
Answer
The CPE terminates the loop towards the FXS. The FXS ring trips on loop detect,
depending on the ring cycle. The FXS transmits A and B bit = 0 towards the
network, terminates the ring back tone and opens the audio path.
CPE
Disconnect
The CPE removes termination from the loop. The FXS transmits both A and B
signalling bits = 0 toward the network. The network responds and the FXS receives
an A bit = 0 and ignores the B bit. The FXS opens the tip toward the CPE and
returns to the idle state.
Network
Disconnect
From the network, the FXS receives an A signalling bit = 0 and ignores the B bit.
The FXS opens the tip toward the CPE and transmits both A and B signalling bits
= 0. The CPE responds to the open tip from the FXS by removing Loop
Termination.
Call Originated
from CPE
The CPE grounds the ring lead to the FXS application module. The FXS
application module transmits both A and B bits = 1 toward the network. After 100
ms, the FXS then grounds the tip. The CPE terminates the tip to ring and removes
ring ground. The FXS audio path is active.
PLAR
Private Line
Auto Ring
The PLAR is used in pairs on opposite ends of network. The FXS application
module transmits only two signalling states toward the network:
✦ Loop open from the CPE to the FXS application module, A and B signalling bits
equal 1,
✦ Loop closed from the CPE to the FXS application module, A and B signalling bits
equal 0 and opens the audio path.