Esa Call Processing - Nortel DMS-100 Series Maintenance Manual

During ESA mode, the system handles all intracalls through the ESA
processor. The ESA processor contains a subset of the translations data found
in the DMS CC.

ESA call processing

When the OPM is in ESA mode, the ESA CC processes line-to-line calls. The
following figure shows the basic call processing structure of the ESA CC.
The ESA CC has one queue. The system sends all messages from the server
to this first-in, first-out queue for call processing. Before call processing
begins, the system needs terminal data. The system gathers terminal data from
the static data downloaded from the DMS CC and the data stored in the
terminal status table (TST).
Terminal status table
The TST has an entry for each line appearance that the ESA processor can
handle. Each entry has two bytes and each byte contains a data structure. The
two data structures are the following:
• Unprotected line data (ULD): The ULD helps the ESA CC decide what
action to take when an event message arrives from a terminal. An event
message establishes or changes a line state. The ULD also keeps track of
errors that a line generates during call processing.
• ESA call process block (CPB): The ESA CPB stores the number of
origination attempts for a line. After successful completion of an
origination, the TST stores the index of the call in a CPB.
DMS-100 Family OPM Maintenance Manual ISN07 (TDM)/SN07 (DMS) and up
ESA maintenance overview 4-11