Verilink PRISM 3030 (34-00208.L) Product Manual - Manual (Page 98)

88 A PPENDIX B: FXS V OICE A PPLICATION M ODULE
removes the ground from the tip toward the CPE and sends an A bit equal 0 and a
B bit equal 1 toward the network. This is the idle state.
Loop Start
Signalling
(MEGACOM)
Idle
State
The FXS application module applies the tip ground and
−
48 VDC on the ring
towards the CPE. The CPE tip and ring is open toward the FXS. The FXS
transmits 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 from the network and responds
by transmitting both A and B signalling bits = 1 for 200 ms before returning A
and B signalling bits = 0. The FXS applies ring voltage towards the CPE and
transmits the ring back tone towards the network, coincident with the ring cadence.
CPE
Answer
The CPE terminates tip to ring in response to the ring voltage. The FXS
recognizes the loop termination, removes ring voltage and ring back tone, enables
the audio path, and transmits both A and B signalling bits = 1 towards the
network.
CPE
Disconnect
The CPE removes the loop termination toward the FXS. The FXS transmits both A
and B signalling bits = 0 toward the network. The network responds and the FXS
receives an A signalling bit = 0 and ignores the B bit. This is the idle state.
Network
Disconnect
From the network, the FXS receives an A signalling bit = 0 and ignores the B bit.
The FXS responds by transmitting both A and B signalling bits = 0 toward the
network and removing tip ground for 500 ms toward the CPE. The CPE removes
tip to ring termination. This is the idle state.
Call
Originated
from DTE
The CPE applies termination between the tip and ring towards the FXS. The FXS
transmits A and B signalling bits = 1 toward the network. The network returns a
dial tone. The CPE then dials the number. The FXS receives an A signalling bit =
1 and ignores the B bit when the network answers.
Loop or Ground
Start Signalling
with Reverse
Battery
(MEGACOM) This is the same as for Loop Start or Ground Start MEGACOM except that when a
CPE-originated call connects, reverse battery is applied to the CPE tip and ring leads.