Chapter 1: ISDN: A Better Way Of Working:

ISDN: What Is It?

At its simplest, ISDN is a telecommunications technology designed to carry the power of the worldwide digital network directly to the desktops of end users.

Using the simple concept of dialing a connection when and where it's needed, ISDN offers reduced digital communications costs, almost unlimited flexibility in gathering and using bandwidth, clearer voice conversations, improved employee productivity and literally hundreds of exciting new applications that were either not possible or not practical before.

And while ISDN is often found as part of a larger connectivity solution that includes many of today's emerging telecommunications technologies - ATM, SMDS, Frame Relay and others - it is, in fact, quite different. For while most of those technologies are designed and priced to link corporate or enterprise systems together at high speeds, ISDN is designed and priced for the individual end user.

The primary purpose of ISDN, in fact, is to "close the loop" from the worldwide digital telecommunications network to the desktops of individual users - from corporate managers and engineers to doctors, students, real estate agents and more.

What it brings to these users is a varied and almost limitless range of powerful capabilities:

Dialed digital connections. It is no longer necessary to use dedicated lines to gain the benefits of digital speeds or connectivity. The flow of digital information now begins at the user's desktop, and links it to the desktops of users around the world.

All types of information. From voice and data, to complex images, f ull-color video and stereo-quality sound, all are transmitted with digital speed and accuracy through what is now a totally digital network.

Much higher data speeds. ISDN replaces today's slow modem technology with speeds of up to 128Kbps (kilobits per second) before compression. With compression, users in many applications today can achieve throughput speeds of from 256Kbps to more than 1,024Kbps - more than a megabit per second.

Greater accuracy; virtually no problems. Digital lines are almost totally error-free, which means that the slowdowns and errors typically encountered in today's modem transmissions are no longer a problem.

Multiple devices and multiple numbers on the same line. A single ISDN line can serve as many as eight devices - telephones, facsimiles, desktop computers and more. Each device, in turn, can be assigned its own telephone number, so that incoming calls can be routed directly to the appropriate device. While some tariff restrictions apply, enormous flexibility is possible.

Multiple calls or transmissions on the same line. Any two of these devices can be in use at the same time for voice or data transmissions, and the two "lines" can also be combined for higher data speeds. In addition, an almost unlimited number of lower-speed data transmissions - for e-mail, credit-card authorizations and the like - can also go on at the same time.

Standard telephone wires. In most cases, the same copper wires used today for what is typically called plain old telephone service - or POTS - can be used successfully for ISDN. Which means that most offices and homes are, in fact, ISDN-ready today.

Much better voice telephone service. Often overlooked in the excitement of faster, more accurate data transmissions is the fact that ISDN represents the next generation of voice telephone service. It offers absolutely quiet, clear worldwide conversations every time, plus a host of powerful call management and call handling capabilities.

Seamless connections to other networks. ISDN lines can be connected, or interworked, to virtually every other voice, data and packet network in the world - from a voice call across the street, to a private data network in a remote country, to an X.25 terminal in a developing nation.

ISDN offers, in short, a faster, better, more economical way to communicate.