Nortel DMS-100 Series Maintenance Manual page 176

3-16 ESA maintenance overview
The first byte (unprotected line data) in the TST is divided as follows:
The ESA line-audit process returns the line to service.
297-8211-550 Standard 05.01 August 1999
error count/cause: The first four bits contain the count of the errors the
software of a line detects. Each error increases the count. If the error
count reaches a preset threshold, the system removes the line from
service. The system records the last cause of the error in place of the
error count.
line state: The last four bits contain the state of the line. The line states
are as follows:
— ManB: The line is manually busy. The system suspends service to
the line and ignores any messages from the line. Calls cannot
terminate to this line.
— idle: The line is equipped. The line is call-processing idle now. The
line looks for an off-hook condition. The system treats origination
messages from the line as a call origination. Calls can terminate to
this line.
— originated: The line originated a call, but resources are not available
to service the line. If still off-hook, the line reoriginates the call after
a 1 s delay. The system can receive an on-hook message before the
1 s timer expires. If this message occurs, the system puts the line in
the abandon state. The line can reoriginate only three times before
the system puts the line into the lockout state. Calls cannot terminate
to this line.
— abandon: The line waits for another origination attempt. Any
off-hook or on-hook message puts the line into the idle state. When
in the idle state, idle scan for an off-hook condition starts. Calls
cannot terminate to this line.
— CPB: The line is call processing-busy. In this state, a CPB is
associated with the line. The associated CPB index is in the second
byte of the TST. The system directs messages the line generates to
the associated CPB index. Calls cannot terminate to this line.
— lockout: The line is not involved with an active call. There is no
CPB associated with the line, but the system monitors the line for an
on-hook condition. An on-hook message causes the line to return to
an idle state. When in the idle state, the idle scan for an off-hook
condition starts. Calls cannot terminate to this line.
— SysB: The system detected too many errors on the line. The system
puts the line out of service. The system stores the last cause of the
error in the error count/cause byte of the TST. The system ignores
all messages from the line.