Nortel DMS-100 Series Maintenance Manual page 392

9-28 Trouble isolation and correction
MTA for the RCS line card
When a subscriber loop connects to the MTA, it can be tested from the LTP
or the ALT levels.
The RCS line cards have test access (TA) and cutoff (CO) functions on the
same relay. When this relay operates, the line card is cut off from the MTA
and metallic testing is restricted to subscriber lines. The name of this
process is the OUT testing configuration.
While the subscriber loop connects to a metallic test pair for testing, the
associated line card connects to a passive termination for testing. The RCS
must place the correct termination across the tip and ring of the RCS line
circuit. The termination is in response to A- and B-bit patterns the SMS
sends to the RCS. The Bellcore document Digital Interface Between the
SLC-96 Digital Loop Carrier System and a Local Digital Switch describes
these patterns.
Along with line circuit and subscriber loop tests, the system supports the
station ringer test.
The silent switchman test is not supported. Supporting the silent switchman
test places the subscriber loop in cutoff. The MTA testing to subscriber
loops has limits. The placement of the subscriber loop in cutoff interferes
with the ringing. The RCS has a single relay that connects ringing and TA
297-8231-550 Standard 09.01 August 1998
C
M
TM
CO
CO
RCS LINE CARD
MTA
TA
X
X
TA
TIP
RING