Nortel Enterprise 1000 Reference Manual page 111

E&M Type II signaling
Figure 42 on page 115 shows E&M Type II signaling patterns for incoming
and outgoing calls. Figure 43 on page 116 shows Type II signaling patterns
for a tandem connection where the originating end is senderized and the route
is over a CO trunk (CCSA not applicable).
Type II signaling uses four leads: M, SB, E, and SG. Instead of changes of
state between battery and ground (M signals) or open and ground (E signals),
the trunk signals by closing the contacts between the lead pairs M and SB.
Signals are received by detecting current flow between lead pairs E and SG.
On incoming calls, the far end seizes the trunk by shorting the E and SG leads
together. This transmits the ground from the SG lead to the E lead (in Type I
signaling the ground to the E lead comes from the far-end). Dialing is done
by opening and closing the E/SG contacts. Since the SB and M leads are also
used as the ESCG and ESC leads, respectively, for echo suppression, echo
suppressor control cannot be used with Type II signaling.
Note: M, SB, E, and SG designations are Electronic Industries
Association and Telecommunications Industries Association (EIA/TIA)
conventions. These leads are also known as MB, MA, EA, and EB,
respectively, in Succession CSE 1000 conventions.
Release control
Release control of a call made over a trunk is specified in LD 16. Disconnect
supervision is specified for each trunk group independently. The two options
available are EITHER or ORIGINATING party control. These can be
specified for the Succession CSE 1000 end (near-end), or for the CO or other
PBX end (far-end). Joint party control can also be specified for the far-end.
Duplex signaling
Duplex (DX) signaling makes use of the voice transmission leads for
signaling as well as for voice transmission. For descriptive purposes, the lead
pair Tip B/Ring B is designated the signaling pair. The other pair Tip A/Ring
A conducts current in the opposite direction to balance the overall current
flow between the near and far ends. During signaling, current flows through
both Tip B and Ring B leads in the same direction.
Succession Communication Server for Enterprise 1000 Circuit Card Reference Guide
NT8D15 E&M Trunk Card Page 111 of 236