Carrier Access Access Bank II SNMP - Manual (Page 107)

4-Wire E&M/TO Configuration
11-4 9/24/01
interface incorporates a signaling current detector (the “ear” listening to the line). The multiplexed or
carrier channel equipment always originates signaling on the E-lead coming from the transmission
line. The signaling current detector is found on the M-lead going toward the transmission line.
The 4-wire E&M/TO voice card can be optioned to operate either as channel equipment or switching
equipment. Since the Access Bank II - SNMP typically operates as a voice and data multiplexer, the
card is usually configured as channel equipment. This is referred to as tandem operation because the
card operates in tandem (i.e. back-to-back) with another transmission device.
Table 11-1 lists the generic functions performed by the Detector/Detector Return and Driver/Driver
Return when the 4-wire E&M card is configured to operate as Channel Equipment or Switching
Equipment.
Table 11-1: Detector-Driver Functions
Figure 11-3: E&M Signaling Type 1
Channel Equipment Detector is on M-lead function
Driver is on E-lead function
Switching Equipment Detector is the E-lead function
Driver is the M-lead function
M-Lead
Detector
-48V
E-Lead
Detector
-48V
M
E
E&M Type 1
Normal Mode
(Terminating)
(Channel Equipment)
Tandem Mode
(Originating)
(Switching Equipment)