Printer Friendly

The second coming of ISDN.

For years. ISDN was derided as the acronym for "It Still Does Nothing" rather than Integrated Services Digital Network. But that is changing. thanks to the growing ranks of telecommuters and small remote offices in need of high-speed dial-up access to the Internet or the corporate LAN.

Responding to the demand, the Baby Bells are finally giving some attention to ISDN, making the service more widely available, if still somewhat overpriced.

At the same time, equipment suppliers are zeroing in on the ISDN mini-boom with attractively priced and standards-compliant terminal adapters and routers. These devices give users the flexibility to combine voice, data and fax over a single line or dedicate the line to high-speed data or even video traffic on demand.

For telecommuters, the preferred ISDN service is the Basic Rate Interface (BRI), which provides two 64 kb/s B channels for carrying traffic and a single 16 kb/s D channel for out-of-band signaling. The two B channels can be combined, or multiplexed. to provide a 128 kb/s link. With data compression, data rates of 512 kb/s or more arc possible, making ISDN suitable for videoconferencing as well as high-speed data applications.

When the B channels are not multiplexed, BRI delivers two separate links so a user can send a fax or have a phone conversation while maintaining the data link. This flexibility makes ISDN an attractive service for telecommuters and others working at home or in a small remote office. Further, ISDN is a user-friendly service in that it operates over copper wiring and works and looks like a traditional telephone connection.

Larger remote offices may opt for multiple BRI connections, or for the Primary Rate Interface (PRI) service, which provides 23 B channels and a D channel.


BRI and PRI tariffs vary widely from region to region, but typically have a fixed monthly charge and usage fees, similar to telephone service. Bell Atlantic charges from $100 to $170 for installation of BRI service and a monthly fee of $30 to $50, while Pacific Bell charges $125 and $26, respectively.

For PRI service, Pacific Bell increases the installation charge to $750 and the monthly fee to $250. This compares with a $700 installation charge and monthly fee of $450 to $800 for PRI service from Bell Atlantic. Usage charges are additional.

Bell Atlantic has made ISDN service available in 95% of its region, and most other Baby Bells are providing ISDN to between 80% and 90% of their service areas. One of the laggards, Southwestern Bell, says it expects to make ISDN available in its entire five-state region by the end of the year.

ISDN connections can now be ordered in 261 U.S. metropolitan areas, with more to come. According to the Yankee Group of Boston, Mass., ISDN use next year will grow to 1.5 million lines, or nearly three times last year's figure.

Two hotel chains, Hilton Hotels and Hyatt Hotels, have also begun offering ISDN service in some of their properties to cater to mobile users and to support videoconferencing and high-speed data connections from their meeting rooms. Hotel guests can usually access the service from their rooms with about 30 minutes' notice.


Telecomm deregulation could bring further competition to the ISDN market and, with it, lower charges and fees, improved support with features such as ISDN help desks, and new services. Some carriers are already starting to offer bundled services with frame relay and Internet access to make ISDN more attractive to corporate network managers.

Deregulation, though, may also bring competition in the form of new highspeed options such as ADSL (asymmetric digital subscriber line), which can deliver up to 8 Mb/s over existing copper telephone lines. and modems for operation over standard TV cable at speeds to 30 Mb/s.

ADSL and cable modems threaten ISDN because they are suited to applications such as Internet access, telecommuting and remote access which have fueled the recent growth of ISDN. In these applications, the upstream traffic is generally much less than the downstream traffic. which plays to the strength of ADSL and cable modems, which are asymmetric by design.

For the moment, though, ISDN still has the edge because it is available today. whereas ADSI. and cable modems are two to three years away from being practical alternatives.


Convinced that ISDN is here to stay, a number of leading vendors are targeting the equipment market. The simplest device is the terminal adapter, which equips a PC or other unit for use with ISDN. Most terminal adapters are external devices, but a number have recently become available as PC cards and more are expected. Market projections estimate that by the year 2000, some 4 million ISDN cards will be sold annually. Mobile users can buy combination cards that support BRI service but also function as V.34 modems for use where ISDN service is not available.

While terminal adapters are suitable for home use, larger offices may need an ISDN bridge or router. Bridges are cheaper and easy to use, but they may forward data unnecessarily, making it difficult to control the flow of data over ISDN and driving up usage fees.

Routers send data over the network only when needed and are easier to scale in larger and more complex networks. 1SDN routers may also come with a number of software-based options, including B-channel aggregation, data compression and simplified set-up for Ethernet and token-ring LANs.

Ascend's Pipeline 25 adapter is a popular choice for telecommuting and Internet access. Priced at $895, it comes with an ISDN port, 10Base-T port, serial port for setup and control, and two analog phone ports. The device will automatically drop one B channel during an ISDN session to receive an incoming analog call or initiate an outgoing one. Options include IP routing and Stac compression with throughput to 512 kb/s. It does not support multiprotocol routing; for that you need the Alameda, Calif., firm's $1,195 Pipeline 50.

Shiva Corp. of Bedford, Mass., has added an integrated ISDN BRI hardware module for its LanRover/Plus remote access server and equipped its operating system with ISDN deployment features. Its Integrator 500 ISDN router for IP/IPX LAN internetworking makes use of the actual circuit costs to determine routing, so evening LAN traffic may be routed over the ISDN link: for example, if usage is not metered at night.

For low cost and ease of use, the DirectRoute family of ISDN routers from Symplex Communications (Ann Arbor, Mich.) are tough to beat, For simplicity, the routers use a text-based menu that is easy to understand. As a cost-saving measure, line caps can be set by call, day or month. and you can block calls at certain times of day or require that they originate from a specific source.

3Com's NETBuilder Remote Office routers support ISDN BRI connections to provide end-to-end digital dial services to remote LANs and to the Santa Clara firm's remote access server, the AccessBuilder 4000 ISDN.

Meanwhile, Microsoft is busy promoting the technology by providing an ISDN performance "accelerator pack" for Windows 95 that helps users optimize their applications for ISDN. It is also collaborating with hardware vendors to help insure broad support for ISDN devices. At the same time, more than 25 vendors of ISDN equipment have announced they are developing ISDN drivers for Windows 95.

Data communications consultant Morris

Edwards is program chairman of the Network Computing Solutions Conference and exposition, or NetCom, to be held in Charlotte, N. C., Oct. 9-10 and in Nashville, Tenn., Oct. 30-31.
COPYRIGHT 1996 Nelson Publishing
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1996 Gale, Cengage Learning. All rights reserved.

Article Details
Printer friendly Cite/link Email Feedback
Title Annotation:Industry Trend or Event; usage to triple in 1997
Author:Edwards, Morris
Publication:Communications News
Date:Aug 1, 1996
Previous Article:Casting a wider 'net.
Next Article:An (almost) unwired world.

Related Articles
Will standard interfaces be enough to turn the tide for ISDN implementation?
ISDN takes center stage at CMA's annual conference this fall.
Videoconferencing: it's more affordable when you use ISDN.
The crux of ISDN: what it does for your business.
ISDN-frame relay link is good for office and remote workforce.
Single B channel effectively extends the office network.
Pipe dreams come true.
Will digital copper catch on? ISDN.

Terms of use | Privacy policy | Copyright © 2021 Farlex, Inc. | Feedback | For webmasters