SECTION
MITL9105/911
O-096-350-NA
5. SYSTEM OPERATION
_-
1
:
-.
,-
:..
(.
._
General
This Part will discuss events which occur within an SX-lOO/SX-200
system during the operation of extensions, trunks, consoles and
SUPERSET 4 electronic telephone sets. From this Part the repair person
should be able to discern a basic working knowledge of the system.
Also in this Part is a series of tables which list error codes and
problems that may occur. These tables will provide a solution to each
problem, or reference a MAP in the appendices for the appropriate
remedial action.
Extension Operation
5.01
Each extension is assigned to a specific equipment number on
a specific Line card (Figure 5-l). When an extension goes
off-
hook, it will complete a circuit and draw loop current. This loop current
will cause the LED (on the Line card) associated with that equipment
number to light. At this time there are up to 31 speech paths available
for assignment to the off-hook extension. Each Line card has an 8 x 32
switching matrix, providing access to 31 speech paths and one Music-
on-Hold (MOH) path (Figure 5-l). The Scanner card will detect the
off-hook condition on the Line card and report the equipment number
to the Central Processor Unit (CPU). The CPU (through its Random
Access Memory or RAM) will find a free speech path and test it, using
circuits on the Tone Control card. After the speech path is tested, the
CPU connects it to the line circuit and a free receiver is located. The
selected receiver, and dial tone from the Tone Control card, are then
connected to the free speech path (Figure 5-2).
5.02 When the first digit is dialed, it is detected by the Receiver card.
(The Scanner card reports to the CPU that the Receiver card
has a digit. The DTMF or DP information is decoded by the Receiver
card.) The digit is read by the CPU. Upon reception of the first digit, the
CPU will inform the Tone Control card to drop the dial tone. The
Receiver card will continue to monitor and decode digits until the CPU
recognizes a digit sequence or determines an invalid sequence. This
digit sequence may access a feature, a trunk, the Supervisor, or an-
other extension. If the option selected is busy, the extension will
receive busy tone from the Tone Control card.
5.03 When an extension dials a sequence that requires the use of a
feature, the CPU must first check that extension’s COS. If the
extension’s COS does not allow access to that feature it will be as-
signed (by the CPU) reorder tone from the Tone Control card. If feature
access is permitted, the CPU will act according to the memory stored
in the RAM. All information will be stored in the system’s RAM by the
CPU. It should be noted that the Scanner card. informs the CPU that the
Receiver card has a digit decoded for each digit the extension dials.
The CPU controls all tones (i.e., supervisory tones that the extension
may receive) switching them on/off at the correct rates.
Page 53
To Next Page
Loading...
