Nortel DMS-100 Series Maintenance Manual page 161

Ringing
The CO determines the type of ringing to employ. The CO sends a ringing
signal to the RLCM over the DS-1 channel associated with the line that the
subscriber calls. This signal directs the RLCM to connect the ringing
generator to the line. The ringing types that the CO provides and that the
RLCM applies are as follows:
bridged ringing (single-party)
superimposed ringing (multi-party)
coded ringing (cadencing)
frequency selective ringing (FSR)
ESA signaling
The ESA feature is an emergency service that provides a subset of
call-processing capabilities. The ESA provides these capabilties when a loss
of communications to the host occurs. This emergency service includes call
processing for basic station-to-station calls in the RLCM for
plain-old-telephone-service (POTS) and MDC lines.
The RLCM with the ESA feature package provides the same tones as a
functioning RLCM. The tones appear on channel 16 of the incoming C-side
ports of the RLCM. The RLCM software provides tone cadence that
interrupts the tone. The tone cadence controls the time switch in the link
control card (LCC) to interrupt the tone.
To provide a tone in ESA mode, the ESA processor sends a start cadence
message to the RLCM. This message specifies the tone required, the
terminal identification, and the cadence times.
When a make cadence message is received, the RLCM performs the
following steps:
1 Break terminal current receive path connection, if necessary.
2 Connect the receive path of the terminal to the correct port.
3 Set up the specified cadence for the tone.
The idle tone uses the start cadence message. The RLCM connects the
receive path to a port that provides idle tone.
DMS-100 Family RLCM Maintenance Manual XPM12 and up
Signaling for RLCM 4-7