N-GEN Communications Web-based Seminars ©NGCS

Seminar - An Overview of Communications Technologies

Module 2 - Data Communications Basics and Legacy Technologies                                                Slide 27 of 45 _________________                                                                                  __________

                                              Mature Networks

                                            Public Switched Telephone Network (PSTN)

                                            Integrated Services Digital Network (ISDN)

_________________                                                                                  __________

A telephone network is a world-wide voice communications network. It has gone through many changes. It's facilities have been used for data communications overlay networks. The equipment and communications are mature. ISDN is another Wide Area Network oriented communication service provided by telephone companies. This network is well suited to consolidate access links and switched connections requiring bandwidth greater than analog modems.

PSTN - A network consisting of multiple switches known as Central Offices. The switches enable one customer to connect to another customer for voice or analogue data communications. The Central Offices range from 1,000 to 100,000 switching connections. Recently PSTN is undergoing tremendous changes to accommodate the Internet traffic.

ISDN - A digital switched network provides 64 K bps and 1.544 M bps connections for remote LAN access, Video conferencing, disaster recovery and PABX - to - PABX.