The Call Control Task and the Layer 3 Controller Task com-

municate via the NL

DATA

REQ and NL

DATA

IND

Primitives The messages that are supported between these

tasks are listed below

CC

SETUP

REQ

Setup Request

CC

SETUP

RESP

Setup Response

CC

SETUP

REJ

REQ Setup Reject

CC

INFO

REQ

Information

CC

DISCONNECT

REQ Disconnect

CC

RELEASE

REQ

Release

CC

ALERTING

REQ

Alerting

CC

BROADCAST

RESP Broadcast Response

CC

CALLPROC

REQ

Call Proceeding

CC

PROGRESS

REQ

Progress

CC

NOTIFY

REQ

Notify

CC

RESUME

RQ

Resume

CC

RESUME

REJ

Resume Reject

CC

SUSPEND

REQ

Suspend Request

CC

SUSPEND

REJ

Suspend Reject

CC

SETUP

IND

Setup

CC

SETUP

CONF

Setup Confirm

CC

SETUP

COMP

IND Setup Complete

CCI

NFO

IND

Information Indication

CC

ALERTING

IND

Alerting

CC

PROGRESS

IND

Progress

CC

DISCONNECT

IND

Disconnect

CC

RELEASE

IND

Release

CC

CALLPROC

IND

Call Proceeding

CC

RELEASE

CONF

Release Confirm

CC

STATUS

IND

Status Indication

CC

ERORR

IND

Error Indication

CC

RESUME

CONF

Resume Confirm

The Call Control Task also communicates with the Tracer

Task using single byte keystroke like commands These

commands are packaged mail messages containing two

bytes the first byte is the Sender Task’s ID the second byte

is the keystroke command The following messages are

sent between Call Control and Tracer

TR

ON

HOOK

ON Hook

TR

OFF

HOOK

OFF Hook

TR

DIGIT

1

Digit 1

TR

DIGIT

2

Digit 2

TR

DIGIT

3

Digit 3

TR

DIGIT

4

Digit 4

TR

DIGIT

5

Digit 5

TR

DIGIT

6

Digit 6

TR

DIGIT

7

Digit 7

TR

DIGIT

8

Digit 8

TR

DIGIT

9

Digit 9

TR

DIGIT

0

Digit 0

TR

DIGIT

STAR

Digit

TR

DIGIT

POUND

Digit

TR

IDLE

Idle ON HOOK

TR

DIALTONE

Dial Tone

TR

DIALING

Dialing

TR

RINGING

Ringing

TR

BUSY

Busy

TR

CONVERSATION

Conversation

TR

RINGBACK

Ringback

TR

ERROR

Error

252 Management Entity Task

The Management Entity Task is closely coupled to the ac-

companying Network Management Entity design and to the

terminal hardware configuration Implementation design de-

cisions have been made that make the Management Entity

Task unique to a particular application while still following

the general requirements of the CCITT Specifications Modi-

fications will be required in the Management Entity Task

prior to its successful operation in a particular application

environment The Management Entity Task that is included

in the HPC ISDN Software Package presumes a particular

hardware configuration and Central Office Software imple-

mentation

The Management Entity Task communicates with the Layer

3 Controller Task the Layer 2 Controller Task and the Lay-

er 1 Device Driver Task via the System Mail Utilities

The Management Entity Task has the following responsibili-

ties

26 SYSTEM UTILITIES

The system utilities initializes the HPC system upon power-

up and provide support for various machine specific fea-

tures of the HPC

261 Power-Up Reset Main Task

This task is the entry point upon system power-up The Main

Task is responsible for

Initializing the general HPC Hardware

Initializing the HPC Executive Data Structures

Queuing up the Tasks on the Ready Queue

The Main Task starts with the highest priority 255 After

running the Main Task has served its purpose and is re-

moved from the system by waiting on a semaphore which is

typically never signaled

262 Nonmaskable Interrupt (NMI) Handler

Since terminal power is generally a concern the HPC can

go into an idle low-power mode when the Terminal Equip-

ment is idle In this mode the HPC is awakened via an NMI

prompted by a local off hook indication or by a far-end line

10