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ISDN

Introduction

This guide is designed to give you the facts you need to implement an ISDN for your business. The various sections are listed in the box on the right. You can choose to read this guide from beginning to end, or jump directly to a section of interest by clicking above.

Speed

ISDN connections allow for much faster data transfers than ordinary analog lines. An ISDN BRI line consists of two bearer channels and one data channel. Each bearer channel can carry 56,000 or 64,000 bits per second (bps) depending on the local provider. This is in marked contrast to the fastest analog modems which operate at top speeds of only 28,800 to 33,600 bps.

In practice, ISDN's advantage over analog lines is even more pronounced. ISDN lines dial and connect extremely fast, often in less than a second. Once connected, the line is perfectly clear, which means that transmission occurs at the full transmission rate of 56,000/64,000 bps. In contrast, analog modems are often forced to step down to 20,000 bps or slower transmission rates to accommodate lower quality phone lines.

In some areas, ISDN channels can be combined, or "bonded," to create a single 128,000 bps connection. This offers connections that are nearly five times as fast as a typical 28,800 bps analog modem.

Practical Applications

ISDN applications are growing as the service becomes more popular and accessible.

Internet Access

One popular use is connecting to online services or the Internet. ISDN allows for much faster downloading of graphics, audio and video, minimizing the World Wide Wait. Although ISDN connections are not available from all online providers, an increasing number now offer them.

Telecommuting

An ISDN line in the home can be used to connect to a corporate network for much less money than a dedicated line. Yet ISDN is much faster than a regular modem, allowing home-workers to access databases or other large applications from corporate servers without encountering painfully slow response times.

Video Conferencing

Regular telephone lines are too slow for most current video conferencing applications. However, one or more ISDN connections is often enough for desktop video conferencing. Software on the market is increasingly targeted for ISDN service, with a new ISDN-based standard emerging to permit different video conferencing systems to communicate.

Backup for a Dedicated Data Connection

Because ISDN terminals can dial and connect so quickly, critical data connections can be shifted to an ISDN backup if a main line goes down. Since ISDN is a dial-up service, businesses will pay much less keeping an ISDN line available for backup than paying for a second dedicated line.

Necessary Equipment

Using ISDN requires an ISDN terminal adapter, or "modem," at both ends of the connection. This device translates your computer's signals into the appropriate codes for ISDN. Although not technically modems, these units are manufactured by modem companies and are packaged to look like standard analog modems.

Getting Service

ISDN service is purchased from your local telephone service provider. It is not available in all areas, so you should call your local phone company before purchasing any equipment.

Setting up an ISDN line tends to be very complicated. There are more than 50 different ways to implement ISDN, depending on what equipment is installed at the local telephone company exchange. Most local telephone services have special help lines for businesses purchasing ISDN service.

Alternatives to ISDN

Although ISDN is much faster than an analog modem, it is not the only high-speed connection option on the market.

One emerging alternative is the cable modem. These modems work on the coaxial lines installed by cable companies. Cable modems promise speeds five to ten times as fast as ISDN, although they are still in the testing phase.

Another promising technology is ADSL, or Asymmetric Digital Subscriber Line. ADSL is a new way of using standard telephone lines for high-speed transmissions. ADSL will allow speeds of up to 6.1 million bits per second downstream (to the user) and 640,000 bps upstream.

Pricing

ISDN installation fees vary depending how far you are from a local telephone company office. You can expect to pay anywhere from $40 to $400 for installation.

Once an ISDN line is installed, you must pay a monthly ISDN fee, which can range from as little as $15 to more than $100 per month.

Currently, most ISDN plans do not charge per minute for local calls. However, some telephone companies are now switching to per minute or per hour charges for ISDN calls due to heavy usage.

ISDN terminal adapters start at approximately $300 for the most basic units. Units designed for networks or multi-line routing can easily rise above $2,000.

Special Tips

To Find Out If You Can Get ISDN

Intel offers an ISDN page on their web site to help you find out whether ISDN service is available in your area.

Bonded Connections Cost more

Keep in mind that a bonded connection often results in two simultaneous long distance charges, thus increasing your phone bill.

ISDN Doesn't Work in a Brownout

Do not replace all of your conventional phone lines with ISDN lines. ISDN terminals need an external source of power, which means that you will be unable to use the phone if the electricity goes out.