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Isdn For Small Business Essay, Research Paper


The following will discuss the application and analysis ISDN (Integrated Services Digital Network) to the residential and small business user. ISDN is a digital connection of phone lines from the customer to the telephone exchange. Digital communication is able to transmit all types of communication required today. These are voice, data or computer and imaging or fax.

Data communications are in high demand today and it is difficult to understand. This article will help to inform a residential or business user of the aspects of a higher speed data connection.

The article will focus on Basic Rate Interface (BRI) which is the type that is most applied to small businesses and residential users. BRI ISDN was developed to be the digital connection replacing the now existing phone lines from users to the telephone company. There are many considerations and alternatives to ISDN. This can range form regular phone connections to a digital satellite dish. The article is offers a worthy discussion for anyone contemplating a higher speed internet connection in the near future.









Usage of PRI 3

How BRI Works 4










Works Cited 10

List of Illustrations

Figure 1 PRI Usage .3

Figure 2 BRI Channels 4

Table 1 Wisconsin ISDN Rates .6


Integrated Services Digital Network (ISDN) is a high speed phone connection that can be used for voice as well as data. ISDN completes a digital connection between a user and the telephone provider.

Small businesses and individuals are requiring internet access to conduct day to day transactions. The connection speed to the internet could be the key to a business s success and a source of unnecessary expense to an individual. This can be a confusing and complicated process.

Today an individual or business has numerous options for a connection to the internet. This ranges from a digital satellite disk to a standard phone line. ISDN offers great possibilities for the commercial business as well as the residential user.

Data communications is in high demand today and is difficult to understand. This article will help to inform a residential or business user of the aspects of higher speed data connection.

ISDN Development

Rapid advances in computer and communication technologies have resulted in the increasing merger of these two fields. The same digital techniques are being used for data and voice. Merging and evolving technologies in the data and voice transmission field, coupled with increasing demands for efficient and timely collection, processing, and dissemination of information, are leading to the development of integrated Systems that transmit and process all types of data. The ulti-mate goal of this evolution is the integrated services digital network (ISDN). (Stalling, Van Slyke 199-200)

Intention of ISDN

The ISDN was developed to be a worldwide public telecommunications network to replace existing public telecommunications networks and deliver a wide variety of services. Most of the world’s existing telephone network is already digital between the telephone exchanges. The only part that typically is not digital is the section that runs from the local exchange to your house or office. ISDN makes that final leg of the network digital.

Uses of ISDN

ISDN is a technology capable of transmitting data at speeds up to 128K. This is significantly faster than you’ll get with standard 28.8, 33.6, or 56K analog modems. In addition to speed, an ISDN connection lets you operate a number of telecommunications devices simultaneously using a single line. (Ameritech) ISDN is ideal for telecommuting and high speed internet connection.

Types of ISDN


There are several types of ISDN service, but the most appropriate type for individual computer users is the ISDN Basic Rate Interface (BRI). Another variety of ISDN is Primary Rate Interface (PRI). PRI is a high -volume service used by business with large communication needs.

Usage of PRI

PRI can handle either 23 or 30 bearer channels and can operate at 1.544 and 2.048 Mbytes. (Stalling, Van Slyke 201 -204) It’s mainly used for connecting large networks directly or connecting a company’s various backbones via ISPs (Internet service providers). Figure 1 is a conceptual view of the PRI ISDN.

How BRI Works

BRI makes sense for small branch offices or residential users. Basic Rate Interface ISDN divides the telephone line into 3 digital channels: 2 “B” channels and one “D” channel, each of which can be used simultaneously. The B channels are used to transmit data, at rates of 64k or 56k (depending on your telephone company). The D channel does the administrative work, such asetting up and tearing down the call also communicating with the telephone network. With two B channels, you can make two calls simultaneously. This is displayed in figure 2. The B channels in BRI also can be aggregated to act as a single channel running at 128 BPS, more than four times faster than a 28.8 BPS modem.

With some ISDN equipment, the channels can be aggregated dynamically. This is useful when additional bandwidth is needed for downloading a large file. It also means the user pays for the bandwidth only when it’s needed: Once the file is downloaded, the ISDN router is disconnected automatically, saving telephone connect charges.

Usage Configuration

Equipment needed

There are a few items needed for ISDN connection, a terminal adapter and an ISDN-capable internet service provider (ISP). Just as analog phone lines need a modem for computer communication, ISDN lines require device called a “terminal adapter.” A terminal adapter can have the following configurations available:

 Additional ports for connecting regular telephones, answering machines and fax machines to the ISDN line.

 Support of custom calling features including caller ID, 3-way calling, call forwarding, call waiting and voice mail.

 The ability to have several PCs or LANs share the same ISDN line. (Leckus)

In addition to the configuration the telephone company must do at their end of your ISDN line, there are some configurations you must do at your end. If you are having the local telephone company fully install your service, the telephone company will make these configurations seamless for you. If you are supplying the end user interface, terminal adapter, the telephone company will supply you with three pieces of information to make your ISDN service work:

 Switch type

 Phone numbers

 SPID(s) – Service Profile Identifier(s) (Leckus)

Most ISDN hardware adapters need to know what type of switch they are connected to. The switch type simply refers to the brand of equipment and software revision level that the telephone company uses to provide you with ISDN service. There are only a few types of switches in the world and usually just one in countries other than the United States. (Daum) You will need this in order to have your equipment connect to the telephone company’s equipment.

The second type of information is your ISDN phone number or numbers. In some cases, each B channel on an ISDN line has its own number, while in other cases both B channels share a single phone number. (Daum) Your telephone company will tell you how many numbers your ISDN line will have. Separate numbers may be useful if you plan to take incoming calls on your ISDN line.

The last type of information is the Service Profile Identifier (SPID), which is only used in the United States and Canada. The SPID usually consists of the phone number with some additional digits added to the beginning and end. The SPID helps the switch understand what kind of equipment is attached to the line, and if there are multiple devices attached, it helps route calls to the appropriate device on the line. (Leckus)

Rates and Charges

Explanation of Charges

Assuming you can get ISDN, the next question is probably “What does it cost?” ISDN rates, known as tariffs, vary by phone company. ISDN pricing generally has three components. These components are also displayed in table 1.

 Installation Charge – this is a one-time charge to have the ISDN service installed. Part of this charge may be waived if you commit to keep your ISDN line for a period of time.

 Monthly Charge – this is a recurring monthly charge.

 Usage Charges – this is a charge associated with use of the ISDN line. Typically it is not more than a couple of cents per minute. The monthly charge may include a certain number of hours of free usage each month. Some packages have no usage charges at all, or may waive usage charges during evenings and weekends.

ISDN Service Package

Primary Application Data only Data and voice Data, voice, voice mail,

and call management

Installation Charge $113.05 $123.05 $143.05

Per month $35.43* $42.93* $52.68*

* Price does not include local taxes and surcharges

Configuration Considerations

“Provisioning” is a telephone company term for the configuration of your line on the telephone company’s end. A normal analog phone line comes with a few options or call management features, like Call Waiting or Caller ID, but it is not necessary to choose any of them. An ISDN line, on the other hand, has many, many options, and choices for all of them must be defined in order for the line to function. Telephone companies can have over seventy configurations of ISDN. These consist of basic “D- Channel” service to Alternate Voice/Circuit-switched Data on both B-Channels. The basic rates on installation and usage are just as wide. (Daum)

Usage Considerations

If you expect to make a large amount of local ISDN calls within your organization, you can look for CENTREX ISDN service, which has no

usage charges for calls to other local numbers belonging to the same organization. (Ameritech)

A business should evaluate the time spent on the connection and the time users will have to wait on data to arrive. If you are looking for a continuous connection, such as connecting a web server, to the internet or to another office, a dedicated frame relay or T-l line may make more sense. ISDN is a circuit-switched service, which means it is only connected when it is being used. Leaving ISDN connected around the clock can end up being more expensive than a dedicated line or “leased” line, which has a flat monthly price.

Availability of Service

Unlike analog telephone service, ISDN service is not yet available everywhere. Your telephone company must have installed the necessary equipment in the central telephone office that serves you. Because ISDN is a digital service, it is very sensitive to outside interference. You must be within a given distance of the telephone company equipment that serves you (typically 18,000 feet to the first router).

Furthermore, there can not be any other anomalies near the wiring that might interfere with the transmission. As a result, even if the equipment is installed at the central telephone office, it is possible you will not be able to get ISDN due to line interference or your distance from the central telephone office. To determine whether your particular wiring will support ISDN, the telephone company will perform what is known as a line qualification. (What is ISDN) Most local telephones companies are able to determine availability online at their web site.

Some telephone companies offer will install the proper equipment to a particular area once an order for ISDN is placed. The local telephone company may not have the right equipment in the local central office that serves you. The provider can use “line extension” technology to serve you from another exchange. The use of line extension technology may significantly increase the cost of your ISDN service. Generally, ISDN has better availability in urban and suburban areas, and is harder to get in rural areas.


There some alternatives today if you want more bandwidth at home or at a small business. There are a variety of faster network choices available to larger organizations, but these solutions tend to be priced beyond the reach of most individuals and small businesses. For Internet access or remote access to a corporate LAN, ISDN is a good high speed option available for most people.

Over the next several years, the bandwidth bottleneck for residential and small business users face will be alleviated with new technologies such as Asymmetric Digital Subscriber Line (ADSL) which works over regular telephone wires and cable modems which work over coaxial cable television wiring. Both of these services will offer multiple megabits per second, but it will take the providers time to deploy these technologies. (Stalling, Van Slyke 205) Until then residential and small business customers can take advantage of the lower cost and higher speed of ISDN.


ISDN is a very powerful and flexible service, providing support for solutions as diverse as PC connectivity, burglar alarm monitoring, and virtual PBX telephone services. There are hundreds of options possible uses on an ISDN line both for the large business and for home and small business use. The power and flexibility of ISDN can make it a very complex process to get configured correctly.

ISDN is a digital connection of phone lines from the customer to the telephone exchange. Digital communication is able to transmit all types of communication required today. Data communications are in high demand today. ISDN is a good alternative for a residential or business user needing high speed data connection for a good price

Works Cited

“Ameritech ISDN.” On-line. Internet. 21 Jan.1999. Available http://www.ameritech.com/products/ISDN

Daum, Audry. “The Last Mile: Getting Past the Bandwidth Bottleneck.” Data Communications 21 Sept.1996; 8.

Leckus, Warren. Personal interview. 5 Jan. 1999.

“What is ISDN?” On-Line. Internet. 21 Jan. 1999. Available

http :\www.microsoft.coni/windows/ISDN/whatis.htm

Sallings, William, and Richard Van Slyke. Business Data Communication. New Jersey: Prentice Hall 1998

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