Public Switched
Telephone Network (PSTN)

Topics in PSTN

Introduction

History

An early analog PBX: 100 subscriber exchange (Subscriber controlled call set-up)

An early exchange, call setup

PSTN exchange development

Categorizing switching

Some features in PSTN of ´60

Some features of PSTN of ´60 (cont.)

Present-day PSTN ‘terminals¹’

Present-day PSTN services

PSTN today summarized

Analog local loop interface

Basic telephone terminal

Dual-tone dialing

Basic modules of a modem

What is specified in a modem recommendation?

Some modem specifications

Slide 20

Fax communications over PSTN

PSTN in ITU-T standards (www.itu.org)

More PSTN standards...

Example: Q-recommendations:
Switching and signalling*

Slide 25

If you don’t find it from Recommendations something is lost:  How to use pay phones?

Switching:
Transfer modes & connections