Click Here To Sign Up Online For ISDN Now. You will need to purchase an ISDN Modem and you will need to call your local telephone company and have a ISDN line run to your home or business location.

What is ISDN?

ISDN (Integrated Services Digital Network) is an all-digital communications network designed to bring the power of the digital network directly to the desktop. It is the ideal communications technology for the information age - perfect for students, cyberspacers, travelers, telecommuters, parents, business people, and corporate executives.

ISDN is as easy to use as analog but offers much more. For example, you can utilize the two 64 kbps B channels as individual voice and data lines at the same time. You can use one channel to talk while you're using the second to send data files. Or, with ISDN's BONDING capability, you can aggregate both lines into a single high-speed 128 kbps link for dependable transmission that's four times faster than a 28.8 kbps modem. Other benefits include:

Voice, data and video can all be sent over a single ISDN line. ISDN connections are made almost instantly - typically less than a second - unlike modems and analog lines which require 30 to 60 seconds before any data can be transmitted. Because it's a digital service, ISDN offers near-perfect line quality that's far superior to analog - so line conditions never force you to fall back to a slower speed.

Optidynamic.com is proud to offer ISDN at only $24.95 per month unlimited service.

BASICS OF ISDN

Integrated Services Digital Network (ISDN) is a fully digital communications technology implemented throughout the infrastructure of the existing worldwide telephone network. ISDN uses a standard phone line (a copper wire pair) in a home or office and converts it from a single analog circuit into multiple high speed digital circuits capable of transmitting audio, still images, motion video, and text data simultaneously. ISDN services make possible videoconferencing and other real time data-intensive applications, and it does so at a price comparable to standard analog service.

Standard telephone service requires a separate phone line for each device to be used simultaneously. Not only can multiple lines be expensive, but the amount of information that can be transmitted is limited with analog service; current technology allows 56 kilobits per second (Kbps). ISDN, however, provides multiple channels to operate concurrently on the same pair of wires, and each channel is capable of transmitting at 64 Kbps. Additionally, digital transmissions
allow for reduced noise and interference on the carrier channels. [1]

ISDN provides services and capabilities not available through standard telephone service. ISDN furnishes these services through a digital package when a call is initiated. The digital packet includes information regarding: 1) who is calling, 2) the type of call (data/voice/etc...), and 3) the number dialed, if more than one number is used for a single ISDN line. [1] With the information provided, ISDN equipment can determine how to handle a call, based on user-defined
preferences. Calls can be accepted, rejected or even rerouted. Data calls can even be routed to an Internet Protocol (IP) address. [4]

THE HISTORY OF ISDN

ISDN has been in the making for over a decade and is just beginning to become widely available in the United States. Europe and Japan have enjoyed large-scale deployment of ISDN services for years. North America has just over 70 percent deployment, with availability in most major metropolitan areas. [4]

The International Telecommunications Union Telecommunications Standardization Sector (ITU-TSS), formerly known as the International Telephone and Telegraph Consultative Committee (CCITT), is a United Nations organization that coordinates international telecommunications. It was the intention of the ITU-TSS to standardize global telecommunications by implementing ISDN. The idea of standardization is widely accepted but the implementation of ISDN has been slow in coming. AT&T and Northern Telecom are the two major manufacturers of ISDN switches used by telephone companies. Each manufacturer took
different steps to provide the ITU-TSS standards for their equipment, and the end result has been incompatibilities with hardware and software. The incongruities stifled the expansive deployment of ISDN since telephone companies have resisted purchasing products that are incompatible with
their existing equipment. [4]

National ISDN 1 (NISDN-1) is a United States-specific implementation of ISDN that was adopted by the telecommunications industry in 1991. NISDN-1 was intended to provide conformity to service users regardless of the equipment or software utilized. However, it wasn’t until November 1992 that the Transcontinental ISDN Project 1992 (TRIP ‘92) was held in Reston, Virginia. TRIP ‘92 was a trade show with exhibits from vendors, proving that ISDN
standardized products and services were available along with applications to support them. Also, the exposition featured the “Golden Splice” event which marked the advent of transcontinental ISDN service. [1]

NISDN-1 addresses three areas: 1) standardizing equipment and services, 2) standardizing telephone company procedures for operation, and 3) standardizing communication among central offices. Unfortunately, the NISDN-1 standards are not accepted by all service providers. Southwestern Bell Corp. and U.S. West Inc. do not plan to deploy NISDN-1 services due to incompatibilities with their existing ISDN networks. [1]

HOW ISDN WORKS

ISDN carries voice and data on bearer (B) channels which transmit at 64 Kbps each. (H channels, which are the functional equivalent to B channels, are available and provide faster bit rates.) A data (D) channel, sometimes referred to as a delta channel, operates at 16 or 64 Kbps and provides signaling to construct and tear down a connection, request network services, and route data over the B channels. The D channel can also be used to transmit user packet or frame data at times when bandwidth on the D channel is not required for signaling and control. Utilizing the D channel in this way provides the most efficient use of ISDN. [1 & 4]

ISDN has three different services: 1) Basic Rate Interface (BRI), 2) Primary Rate Interface (PRI), and 3) Broadband (B-ISDN) . BRI is the most common service and was intended to be the most widely available for residential customers. BRI services provide two B channels and one D channel (2B+D). PRI services are implemented differently in North America and Japan than in Europe where they are the most common services. European PRI services deliver 30 B channels
and one D channel (30B+D). North American and Japanese PRI services consist of 23 B channels and one D channel (23B+D). B-ISDN is still under development but will support up to 622 Mbps transmission rates over a fiber optic network. [1]

One major advantage of the ISDN architecture is its dynamic bandwidth allocation feature. Also known as bandwidth-on-demand, inverse multiplexing, and channel aggregation, dynamic bandwidth allocation is the process of combining any or all of the B channels into a single broadband conduit. 128 Kbps is possible with BRI service and 1.536 Mbps with PRI service in North America and Japan. In Europe, PRI configurations can reach 1.92 Mbps due to the
deployment of additional B channels. [4]

For PRI service, the combining of multiple B channels is often programmed into the ISDN switch servicing the location. For network managers, however, new controllers allow real time control over channel aggregation to provide the most efficient use of a network. [5]

Multilink Point-to-Point Protocol (ML-PPP) is an Internet Engineering Task Force (IETF) standard that describes how to manipulate datagrams over multiple B channels to create a single logical connection. Similar in nature to dynamic bandwidth allocation, ML-PPP is specifically designed for Transport Control Protocol/Internet Protocol’s (TCP/IP’s) Point-to-Point Protocol (PPP). ML-PPP provides additional bandwidth-on-demand for remote LAN and Internet access
and ISDN use. Support is currently available through major ISDN service providers and equipment vendors like 3Com. [4]

With existing analog service, a data connection is made modem-to-modem. At all times during the connection a carrier signal is produced by the modems to indicate the presence of a connection; the connection is lost if either modem cannot detect the carrier signal. The problem with maintaining a constant analog signal is that the service provider’s equipment has to continually process the information. If the percentage of data calls through a central switching
office approaches 50 percent, a large strain on the equipment is produced and becomes a problem.

With ISDN connections, no carrier signal is present. Only the actual user data is transmitted and it transfers at a fraction of the time compared to analog service. Therefore, implementing ISDN switches can actually reduce traffic overhead for service providers which reduces their service costs. In addition, ISDN technology swaps one analog line with two digital connections without physically replacing any wires. [2]

BENEFITS OF ISDN

ISDN affords many benefits to service providers and customers. The increasing popularity of ISDN allows pricing that continues to fall and compete with standard analog service. Some of the many benefits are:

Simultaneous audio, video, and data services over a single pair of copper wires reduces infrastructure and maintenance costs for service and subscribers.

ISDN BRI service can use data compression which boosts the 128 Kbps transmission rate to between 256 Kbps and 632 Kbps, depending upon the compression ratio used.

Digital transmissions produce clearer and quieter voice telephone service and more reliable and accurate connectivity than analog technology.

Remote computer users benefit from high performance ISDN connections at home or on the road.

ISDN’s dynamic bandwidth allocation feature accommodates the bandwidth-intensive applications.

Up to eight different devices can be operated simultaneously over a single ISDN line.

LAN protocols such as IP and IPX are better supported by ISDN connections across WANs due to faster connect times (between 1 and 4 seconds) than analog service (between 10 and 40 seconds).

ISDN is compatible with other WAN services like X.25, Frame Relay, Switched Multi-megabit Data Services (SMDS) and higher speed services like Asynchronous Transfer Mode (ATM). [4]

ISDN PRICING AND AVAILABILITY

Certain areas of the country appear to have better access to ISDN than in other regions. Most networks. have upgraded over 80 percent of their switches to ISDN technology. Other regional operating companies (RBOCs) have upgraded as few as 46 percent. In 1995, Dataquest predicted that ISDN installations in 1996 would increase from 247,000 to 448,000 BRI connections in the United States. These estimates predict an 80 percent increase from 1994. [4]

Pricing is inconsistent nationally. Optidynamic has broken through wih a FLAT rate unlimited ISDN connection at only $24.95 no matter where you live.

INSTALLING ISDN

Standard telephone service to a residence consists of four wires (two pairs) over which two separate analog voice lines can operate. With BRI service, the two pairs of wire can theoretically provide four digital phone lines. In practice, however, service providers will oppose connecting more than one ISDN line to any given location. An ISDN installation involves connecting a single pair of wires between the central office and a home or business. The phone company connects their end of the wire pair to their digital switching equipment and terminate the service end with a standard jack that provides a U-interface. The U-interface signaling handles the high speed data transfers in both directions simultaneously over a single pair of wires. [3]

Standard telephones and computer equipment cannot be connected directly to the ISDN line. All equipment must be routed through a device called a Network Terminator 1 (NT1) which is plugged into the U-connector and provides the signal multiplexing onto the ISDN line. The NT1 also needs a power receptacle to operate, from which it can power itself and other devices connected to it. In Europe, NT1 devices are included as part of the service, but in the United
States, deregulation of telephone services forces the customer to provide the NT1 devices just like the telephone equipment. Unfortunately, ISDN is just now gaining popularity and NT1 devices are not as accessible as other telephone equipment. [3]

From the NT1 unit, a four-wire connection called an “S/T” circuit attaches as many as eight ISDN-ready telephones and/or computers. Non-ISDN telephones, fax machines, and computers require special signal handling prior to being connected to the NT1. A terminal adapter (TA) converts the analog phone and computer signals into digital impulses that can be processed by the NT1. [3]

For computers, both internal and external TAs are available, much like analog modems. Internal TA units plug into an Industry Standard Architecture (ISA) expansion slot in a personal computer (PC) and are capable of providing the full 64 Kbps transmission rates. External TAs connect to a serial communications port (COM port) on the back of the PC; however, the transmission rates of these units are limited by the speed of the serial port. In most cases, COM ports will not exceed 19.2 Kbps, and the full bandwidth of the ISDN line is not utilized. [3]

ISDN CONFIGURATIONS

Multiple Line Services

ISDN services can be supplied in three different configurations from the ISDN-ready digital switch to a business or residence. The alternatives are:

1.Through a direct BRI connection from an ISDN switch. One or more BRI connections are made from the central switching office to a business or home. These connections can be made directly to ISDN equipment, or they can be connected through a Public Broadcast Exchange (PBX) or key system. Using a PBX allows devices to communicate with one another without having to make a connection outside the premises. [5]

2.Through ISDN Centrex service. One or more BRI connections are made to ISDN Centrex service which offers the advantage of having the ISDN switch function as the switching system. Therefore an individual or company does not have to own a PBX or key system. Centrex service is provided at a low cost and provides virtual unlimited growth. [5]

3.Through a PRI connection. 23 B channels and one D channel is connected to a business through a PBX. The PBX then provides the switching necessary within the organization. For heavy data traffic, an ISDN router, multiplexer, or controller may be used instead of a PBX to reduce the chance of a bottleneck through the switch.

Single Line and Second Line Services

ISDN services can be installed as an additional utility to complement existing analog telephone service, or it can be installed as the only connection. There are several ways to configure ISDN with these options:

1.ISDN as the only line. All equipment must be ISDN-compatible or linked through a TA.

2.ISDN as the only line using a digital modem. A single ISDN line can provide service to all types of equipment, provided all devices are connected to a digital modem, such as the IBM WaveRunner.

3.ISDN as a second line. ISDN services can be installed to provide high speed digital transmissions for data transfers while analog telephone service remains intact. The only disadvantage with this configuration is that the services remain separate; there is no way to move a connection from the analog service to the ISDN service and vice versa.

DIGITAL SERVICE COMPARISON

Switched 56 Service (SW56)

SW56 provides 56 Kbps transmission rates for data-only applications over existing public phone lines. It is a low-cost alternative to dedicated leased lines and is used primarily for intermittent data swapping between WANs. SW56 is also used to connect ISDN networks in areas where ISDN is not yet available. [1 & 4]

X.25 Switched Service

X.25 is a widely used protocol standard using synchronous data transmission over the public switched network. It provides data rates up to 56 Kbps and most commonly supports applications for order entry, electronic messaging, point-of-sales transactions and credit card verification. ISDN supports X.25 services over the D channel.

X.25 is efficient at handling bursty LAN environment traffic and also provides data security and error detection/correction facilities. Due to its low speed, however, it is not a viable alternative for high speed LAN and WAN applications. [4]

Switched Multi-megabit Data Services (SMDS)

SMDS uses a connectionless networking scheme to connect multi-node LANs through the public telephone network. SMDS is standardized and supports all major networking protocols and therefore can be utilized as the backbone for Ethernet, Token Ring, and FDDI networks. SMDS uses a fixed 53-byte datagram complete with addressing information for data transmission. Data is routed over the least congested path in an SMDS network, providing faster transmission,
added security, and increased flexibility to reconfigure network sites. Deployment of SMDS service is very low; between 200 and 500 customers in North America. [4]

Frame Relay Service

Frame relay service is similar to ISDN in that it is a standards-based technology defined by both the American National Standards Institute (ANSI) and ITU-TSS. Frame relay operates from between 56/64 Kbps to 1.544 Mbps and can easily handle peak volume traffic flow in the LAN environment, due to its bandwidth-on-demand capability. It typically is applied in LAN-to-LAN internetworking and IBM host access and data file transfer environments. Frame
relay is relatively more expensive (as much as 12 times more) than ISDN since it requires a dedicated access line, and it is not as widely deployed as ISDN services. [4]

Cable Service

Cable services, although still under development, will eventually provide residential customers with WAN connections of speeds between 500 Kbps and 30 Mbps. In addition to fast on-line access with built-in TCP/IP-ready WAN links, customers will be able enjoy interactive television. When services are available they will be delivered over standard coaxial cable, just as current services are provided. Eventually, fiber optic or a hybrid fiber- coaxial cable will provide
services. Cable service has two main disadvantages. The first is the reputation for unreliability over existing cable networks. The second is that bandwidth is shared over cable, causing poor overall response for multiple users on a single cable. Also, current cable networks are not optimized for two-way data communications, and internetworking standards are not in place. [4]

Asynchronous Transfer Mode (ATM)

Broadband ISDN is based on ATM technology, which is emerging as a popular method of simultaneously transmitting audio, video, and data. ATM has transmission rates between 1.544 Mbps and 622 Mbps. ATM standards are defined by ITU-TSS, but many details of the implementation of the standards remain in question and ATM WAN services are not yet widely available. [4]

Point-to-Point Dedicated Leased Services

Private leased lines currently make up the majority of all worldwide WAN connections. Point-to-point leased lines consist of a dedicated digital connection between two points, providing security and control. Transmission rates vary between 56 Kbps and 1.544 Mbps in the United States (T1 rates). in Europe, E1 rates deliver between 64 Kbps and 2.048 Mbps. Leased line services provide a fixed bandwidth at a fixed speed. In many cases, leased lines are used at
under 20 percent of their total capacity. Also, leased lines are not efficient at handling bursty network traffic. [4]

APPLICATIONS OF ISDN

ISDN in Business

For business users and even residential subscribers, videoconferencing is the biggest communication advancement that ISDN has to offer. With the simultaneous high speed transfer of voice and video, ISDN can provide real time video communication on a PC that once was only capable on sophisticated systems costing upwards of $100,000. [1]

A shared electronic chalk board is another tool available through ISDN. Ideas and illustrations can be distributed in real time to remote locations so people in other cities or other countries can participate in meetings. [1]

Telecommuting is becoming a rule more than an exception; more and more people are working from home. ISDN provides the facilities for users to tap into central network resources from the privacy of their own homes and do so with the functionality of a network node. Node connections are possible with Serial Line Interface Protocol (SLIP) and Point-to-Point Protocol (PPP). [1]

ISDN in Education

Students will also reap the benefits of videoconferencing by relating with other students worldwide. Using the video capabilities of ISDN allows students to see the surroundings of other countries or speak with pen-pals. The value of videoconferencing in educational settings is unlimited.

Computers have become important learning tools for students. Children are introduced to computers and networking at an early age, and ISDN allows the high speed connections to vast amounts of information and resources.

SECURITY AND DIGITAL NETWORKING

Security issues are a prime concern for digital transmissions. Although data encryption schemes can alleviate the problem, other security issues prevail. The National Security Agency has approached the FCC with legislation that would make possible electronic surveillance of all digital transmissions. The underlying reason stems from the possible use of the telecommunications system by criminal organizations. Without a means to monitor encrypted network traffic, there
could be no detection or intervention of illegal activities taking place over the public network. [1]

THE FUTURE

There is and for years has been a global push to become a digital world. The main evidence of the digital age is the internetworking of computers, providing access to a wealth of resources and information.

ISDN technology, although plagued by political issues, is a cost-effective means to connect communication equipment of all types for those in remote area's.

As the digital world continues to evolve, FIBER, DSL, Wireless Wi-Fi and Cable broadband seem to be expanding and ISDN is being replaced.

LIST OF SOURCES

1.Landwehr, John. The Golden Splice: Beginning a Global Digital Network. December
1992.
2.Gilbert, H. Modems and ISDN. PC Lube & Tune. February 2, 1995.
3.Gilbert, H. Installing ISDN. PC Lube & Tune. February 2, 1995.
4.Aber, Robyn & Hkouri-Haddad, Najib. ISDN and Data Networking. November 6,
1995.
5.Pacific Bell. ISDN Fundamentals. 1995.

How Do I get Started?

You will need to call our office and we will be happy to explain how to get started with ISDN.