C-10 SmartSwi tch 18 00 4.0 U ser Gui de, Rev 01
SLT Connect ion s
SLT (Single Line Telephone) is a two-wire telephone communication mode. In this
mode, the SmartSwitch 1800 presents a telco/PTT interface which looks like a
standard telephone set. The SmartSwitch 1800 can be connected to analog station
ports (extensions) of a PBX. The SLT option provides the appearance of a two-wire
telephone in a loop-start circuit. An SLT-configured voice port on a SmartSwitch
1800 d e te ct s ri ng volta ge and clo ses t he loop du r ing off-hook an d o pe n s t h e loop in an
on-hoo k condit ion.
E&M Connect ion s
E&M is a communication mode used in PBX-to-PBX communications as shown in
the following illustration .
Figure C-5 Inter -PBX Tr unkin g
This type of interface uses a two-wire or four-wire voice circuit plus up to four wires
for E&M signaling. In this mode, the SmartSwitch 1800 of fers an interconnection path
between two PBXs.
PBX E&M tie-line connections usually require multi-conductor dedicated circuits to
support full-duplex voice and separate signaling lines. Typically, eight wires are
required: four for voice (two wires in each direction) and four for E&M signaling. A
few PBXs use two wires (one pair) for bi-directional voice. The SmartSwitch 1800
can interface with either of these circuits.
The E&M interface is d esigne d to connect wi th that of a PBX tie l in e port, and p rovid e
appropriate end-to-end signaling support for a variety of applications. The system
generates the "E" signal to the PBX in response to an inbound signal at the remote unit.
That signal depends on t he application of the remote unit. The local unit will generate
the "E" signal in the following applications:
●The remote unit is configured for E&M signaling, and detects an active "M"
signal.
●The remote unit uses the OPX option, and detects an off hook condition on its
two-wire loop-start circuit.
●The remote unit uses the SLT option, and detects a ring signal on its two-wire
loop-start circuit.