Esa Call Processing - Nortel DMS-100 Series Maintenance Manual

The RCP processor has a nailed-up (direct) communication link with the
DMS-100 CC. The RCP processor is the only processor at the Star Hub that
can communicate with the DMS-100 CC during an ESA exit. The DMS-100
CC must instruct the RCP processor to exit ESA.
When the Star Hub enters ESA mode, active calls go out of service. This action
is known as a cold entry.
During ESA mode, call processing occurs through the RCP processor. The
ESA software is in the RCP and is known as the ESA CC. The ESA CC
emulates the DMS-100 CC and handles line-to-line call processing. The ESA
CC contains part of the translation data from the DMS-100 CC.
This part of the DMS-100 CC data is a snapshot required for all ESA call
processing. The translation data in the snapshot are static data. The Star Hub
does not enter ESA mode until the ESA software in the RCP receives static
data.
The download of the static data to the ESA CC from the DMS-100 CC
truncates some translation data. Static data are not true parts of the DMS-100
CC. The system only supports basic calls. When the Star Hub is in ESA mode,
the system supports plain old telephone service (POTS) and Meridian Digital
Centrex (MDC) subscriber lines.
Note: If while in ESA mode, the Star Module is dropped or taken out of
service, no recovery is supported. This also applies to DS-1 links that fail
between the Star Hub and the Star Module while in ESA mode.

ESA call processing

When the Star Hub is in ESA mode, the ESA CC in the RCP card manages
line-to-line call processing.
The ESA CC has one queue. The system sends the messages from the server
to this first-in first-out queue for call processing. Before call processing
begins, terminal data are required. Terminal data are gathered from the static
data downloaded from the DMS-100 CC and the dynamic data from the
terminal status table.
Refer to the following figure for a diagram of the queues.
DMS-100 Family NA100 Star Remote System XPM15 and up
ESA maintenance overview 5-3