Nortel DMS-100 Series Maintenance Manual page 182

4-14 ESA maintenance overview
The ESA line-audit process returns the line to service.
The second byte in the TST contains the CPB index/origination count. A CPB
is the data base that associates with the active call process. There are only
enough CPBs to handle the maximum number of intraswitched and
interswitched calls. The number of ESA calls that the system can support is
less than the number of lines supported. As a result, there are not enough CPBs
for the available channels. The signaling states and call processing data that
form the CPB are as follows:
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297-8361-550 Standard 04.02 December 2004
state. When in the idle state, the system starts the idle scan for an
off-hook condition. Calls cannot terminate to this line.
— Call processing busy: The line is in a call-processing-busy state. In
this state, a CPB associates with the line. The associated CPB index is
in the second byte of the TST. The system directs messages that this
line generates to the associated CPB index. Calls cannot terminate to
this line.
— Lockout: The line is not involved with an active call. A CPB is not
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 detects too many errors on the line. The system
places 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.
CPB states
— Call processing idle (CP_Idle): The start-up state before call
processing. The system requests line resources (DTR and connection)
at this time.
— Dialing: The SERVER receives the digits. The system performs digit
translation when the system receives a digit report.
— Routing: A transitional state from Dialing or CP_Idle to another state.
— Revertive wait for on-hook: A revertive call, the system waits for the
call originator to go on-hook before the system applies ringing.
— Ringing: The system applies ringing to the call terminator. The system
applies audible ringing to the call originator. If the call is revertive and