Specifications

Ringing system maintenance 5-3
DMS-100 Family DMS-100 Ringing System BASE15 and up
determine if the ringing trip was valid. If the line is found to be on-hook after
ringing trip, the DMS-100 switch generates a pre-trip log report.
To reduce the possibility of these spurious signals from being interpreted as a
valid answer, the duration of the off-hook signal considered as a valid off-hook
has been changed throughout the development of the DMS-100 switch. The
following table lists the duration of an off-hook signal considered as a valid
answer in relation to the DMS-100 BCS release.
Note: The times given are the durations of the off-hook signal after filtering
in the line card. These times are not the durations of the off-hook signal on
the loop itself.
No ring current
The no-ring-current logs appear when the LM or line concentrating module
(LCM) fails to detect ringing current. Although the result of the log is the
same, the events leading up to the output of the log message differs between
the LM and LCM. Following is a description.
Table 5-1 DMS-100 switch responses to ring trips
BCS Ring trip duration Meaning
Pre-BCS 21 0ms - 70 ms Ignore
71 ms - 80 ms Trip ring (audible and power). Apply
fast busy to calling party and output
LINE113 log report
81 ms and up Consider as a valid answer. Trip ring
(audible and power) and scan for
on-hook
BCS21 through
BCS23
0 ms - 70 ms Ignore
71 ms - 200 ms Trip ring (audible and power). Apply
fast busy to calling party and output
LINE113 log report
BCS23 and
beyond
0 ms - 70 ms Ignore
71 ms and up Consider as a valid answer. Trip ring
(audible and power) and scan for
on-hook
Note: An off-hook detected anytime after the pre-trip interval is considered a valid
ring trip.