Nortel Networks 1000S - Manual (Page 26)

Page 26 of 44 System architecture
553-3031-010 Standard 3.00 August 2005
Call Server
The Call Server provides telephony services, such as call processing, and
supports trunking features. It also acts as a database server for
synchronization of configuration information with all MG 1000S systems.
A CS 1000S system can control a maximum of four MG 1000S systems and
Expanders.
A CS 1000S system with one Call Server supports up to 1000 IP Phones. You
can network a CS 1000S system with other CS 1000S systems to support
larger numbers of IP Phones.
Small System Controller card
The NTDK20 Small System Controller (SSC) card in the Call Server is the
primary system processor. It controls the telephony services and call
processing. Each MG 1000S is also equipped with an SSC card.
The Call Server SSC controls the call-processing features of IP Phones and
trunk interfaces when in normal mode of operation.
The Call Server SSC synchronizes the configuration information on all
MG 1000S SSC cards. The configuration data on all MG 1000S SSC cards
always exactly matches the Call Server SSC configuration data.
The card’s Security Device enables the activation of features assigned to the
system, through the use of a series of keycodes.
Media Gateway 1000S SSC card
The SSC card in the MG 1000S controls the MG 1000S interface and
application cards, and acts as a survivable call processor. All MG 1000S SSC
cards are synchronized with the call processing on the Call Server SSC card.
This synchronization enables an MG 1000S SSC card to take over local call
processing if the primary Call Server fails to respond.
If the Call Server fails to respond, each MG 1000S SSC can become its own
independent call processor. This means that in the event of Call Server failure,
one MG 1000S SSC does not act as a Call Server for the rest of the system;
they are all independent.