AT&T AT&T manual Port Circuit Packs, Step-By-Step Call Description

Error Logger: Prioritizes and stores system errors. The errors are stored in three error records (located in System RAM), that are:

●Permanent System Alarms

●Transient System Errors

●Most Recent System Errors.

The Error Logger lights the Alarm LED (located on the Attendant Console) when a serious error is detected.

Operating System (OS): Controls all message and data flow to/from the Memory Circuit Pack, the Arch Angel Driver Interface, to the microprocessors on the port circuit packs, and to the RS-232 driver interfaces. Messages destined for a particular task are queued until the associated task can receive them. When a task has completed a particular process, the next message is obtained from the message queue of the tasks. The OS provides an interval timer that is used to time tasks. Processes that exceed the set interval (about 60 seconds) are terminated by the OS.

Arch Angel Driver Interface: Provides an interface between the OS and Network Control.

RS-232 Driver Interface: Handles the flow of information between the Call Processor Circuit Pack and the peripheral equipment of the system (i.e., System Administration Terminator Advanced Administration PC, Digital Tape Unit, and SMDR Output Device.)

TDM BUS

Provides an electronic link between the system port circuits (including System Resources) and between the Call Processor Circuit Pack and port circuits.

Port Circuit Packs

Each port circuit pack has on-board software that provides for the sending/receiving of Network Control messages and data. Circuit pack status messages are also sent to the Network Control software.

Step-By-Step Call Description

The following is a description of a call originated between two multilane voice terminals.

1.A microprocessor on a station port circuit pack (port controller) continually

monitors associated port circuits for switchhook status/change and button presses.

2.When a user goes off-hook, the port controller detects the change.

3.The port controller s e n d s a n o f f - h o o k u p - l i n k m e s s a g e a l o n g w i t h p o r t

identification to the Call Processor Network Controller (CPNC) via the TDM bus.

4.The CPNC accepts the message and forwards it to the Operating System (OS) via the Arch Angel Driver Interface.

5. The	OS checks a	message	directory to	determine	which task (i.e., software module)
is to	receive the	message.	A function	of the OS	referred to as the “transformer”,

determines it has a message for the Station Call Processing task and queues the message in RAM.

3-47