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To provide bias for a telephone and convert a loop condition into a seizing signal (equivalent to 'M' lead
loop-to-ground), which is then passed transparently to the remote unit. The V100 provides an on-hook
voltage of –48V and supplies 28mA when the telephone handset is off-hook.
2.4.1.2
FXO mode
In this mode the V100 is connected to a 2-wire circuit which generates a ringing voltage (an Office port).
This would normally be an extension port on a PABX.
FXO mode has two functions:
A ringing voltage on the TIP and RING wires is detected (equivalent to 'M' lead loop -to-ground) and the
condition is "answered" by the V100 irrespective of the ringing cadence. The ringing signal is then passed
through the V100 network to the remote telephone.
An active signal from the calling channel within the V100 network is converted into a 2-wire DC loop. This
is seen as a seizing signal by the PABX. The speech path is then open, dialtone is drawn from the PABX
and DTMF dialling may commence.
2.4.1.3
TIE-LINE mode
When the unit is configured to Tie-line mode, the RJ45 port may be connected to the Tie-line card of a
PABX. The port presents a 4-wire voice interface and E&M signals. No ringing voltages are generated by,
or should be connected to the ports in Tie-line mode. The type of E&M interface is defined by the jumper
settings described above.
Standard 10pps dialling is detected on the 'M' lead, sampled and transferred transparently to be output on
the 'E' lead of the remote unit. When the unit is powered off or loses carrier, the 'E' lead presents a busy
signal to the connected PABX.
An active 'M' lead is the corollary of "Off hook" in the case of the 2-wire FXS interface and will request
bandwidth in the same way. This allows a Tie-line port to interact with DBA data channels despite any
dialling pulses on the 'M' lead, which are filtered out by software.
2.4.1.4
E&M Support
In Tie-line mode the voice channels operate a 4-wire speech interface and also
present four wires for the E&M interface: E, EREF, M and MREF. The V100 can be
configured to support two types of E&M signalling interface (types I and V) by jumper
selection.
The V100 defines the 'M' circuit as the input and the 'E' circuit as the output. (The
reverse of most PABXs) Therefore when connecting to the PABX, 'M' should be connected to 'M' and 'E' to
'E'. The 'E' circuit on the V100 provides a contact closure and the 'M' circuit has a current detector. The
'M'lead is sampled and passed to the remote port to be output as a contact closure on the 'E'lead.
V100 Versatile Multiplexer Technical Manual Version 2.2
C H A P T E R
Page 22 of 231
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I N S T A L L A T I O N
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