ISDN: What Is ISDN and How Does It Work?
Telephone networks originally existed as analog, requiring online searchers to use traditional modems to connect to networks. However, ISDN (Integrated Services Digital Network) offered a significant leap forward from analog lines, enabling the simultaneous transmission of voice, data, and even video over a single connection. Learn what ISDN is, how it works, and how to configure it.
What is ISDN?
ISDN, short for Integrated Services Digital Network, is a set of communication standards that enable digital transmission of voice, data, video, and other services over traditional telephone lines. Developed in the 1980s, ISDN revolutionized how we connect and share information. The main purpose of ISDN was to create an end-to-end communication network. It became a popular way for organizations to communicate and transfer data between different locations.
Having a reliable way to make a call and send data is a big plus. This perfectly encapsulates one of the core benefits of ISDN. Users can make phone calls, send faxes, and access the Internet all at the same time.
Integrated Services Digital Network is a development of the Plain Old Telephone Service (POTS). It wasn't just another form of technology, but rather a revolutionary step forward and an improvement upon dial-up. The ISDN Internet service made way for our current cable modem Internet services.
Another notable feature of ISDN is its digital nature. Unlike analog systems, which convert voice and data into electrical signals, ISDN transmits information in a digital format. This type of transmission ensures clearer voice quality, faster data transfer rates, and improved reliability. It also enables the use of advanced services such as video conferencing.
The technology has played a crucial role in bridging the gap between traditional telephony and Internet-based communications.
By utilizing ISDN adapters or routers, users can connect their ISDN lines to IP networks and enjoy the benefits of Voice over IP (VoIP) technology. This integration has opened up new possibilities for feature-rich communication solutions.
History of ISDN
As the telephone network grew in the early 20th century, it relied on analog technology. However, this system had limitations, including noise interference and limited data transfer speeds.
Recognizing these limitations, telecommunication companies began exploring ways to upgrade the network to digital. This included research into developing digital switching systems.
ISDN emerged in the 1980s, but it really took off in the 1990s. It was born out of the need for more efficient and versatile methods of transmitting data.
Integrated Services Digital Network offered significant advantages over traditional analog lines. It provided simultaneous voice and data transmission at speeds ranging from 64 Kbps to 2 Mbps, a significant improvement over dial-up connections.
Businesses, especially those requiring reliable and faster data connections, were the first to adopt ISDN. It found use in homes for early Internet access and video conferencing as well. With ISDN, users could not only make phone calls; they could also transfer data, images, and video over a single line.
The emergence of DSL (Digital Subscriber Line) technology in the late 1990s offered significantly higher speeds than ISDN. This, coupled with the increased demand for bandwidth, led to a gradual decline in ISDN's popularity. The widespread adoption of fiber optic networks provided even faster and more reliable connections, further marginalizing ISDN.
While largely replaced by newer technologies, ISDN provided the foundation for the development of more advanced technologies that we use today.
Even though its widespread use has diminished, ISDN is still used in specific niche applications, such as point-of-sale systems and credit card verification, where dedicated connections are crucial.
How does ISDN work?
Integrated Services Digital Network works by using digital signals to transmit voice, data, and other services over copper phone lines. It essentially converts analog signals into digital format for transmission. This allows for clearer communication and faster transmission of information.
ISDN divides a single copper phone line into multiple channels, each serving a specific purpose. The B channel, or bearer channel, carries voice, data, or video information.
It reaches speeds of 64 Kbps each. It's where the actual communication takes place. The number of B channels determines how many simultaneous connections one can use.
The D channel, or data channel, is responsible for signaling information call setup, teardown, and other control signals. This dedicated channel operates at 16 Kbps. It aims to manage the communication happening on the B channels.
When you want to make a call or send data over ISDN, the D channel sets up the connection. Once the connection is established, the B channel handles the actual transmission of the information. The beauty of ISDN lies in its ability to multitask.
Types of ISDN
Integrated Services Digital Network comes in two connection types: basic rate interface (BRI) and primary rate interface (PRI). The configuration that ISDN offers is based on user needs.
Basic Rate Interface (BRI)
BRI is the most common type of Integrated Services Digital Network used in homes and small businesses. It offers two B channels and one D channel (2B + D) with a maximum speed of 128 Kbps.
Each of the two B channels operates at 64 Kbps and can independently carry information. The single D channel operates at a lower speed of 16 Kbps.
Integrated Services Digital Network's BRI configuration provides basic communication needs at lower expenses. Therefore, it's a lower tier of service. BRI can be used for Internet access, video conferencing, and faxing.
Primary Rate Interface (PRI)
PRI caters to larger organizations with higher bandwidth demands. This type supports up to 23 B channels, each with a speed of 64 Kbps, thus providing a combined bandwidth of 1.544 Mbps and one D channel.
Like BRI, PRI has a single D channel operating at 16 Kbps for control signals. It can be used for high-speed data transfer, VoIP services, and video conferencing.
How is Integrated Services Digital Network configured?
ISDN configuration can be a complex process. It typically involves the collaboration of both your Internet service provider (ISP) and, depending on the complexity, an IT professional.
It requires two pieces of hardware: the ISDN Terminal Adapter (TA) or router, and the ISDN line. The TA or router connects your network to the Integrated Services Digital Network line. The line is provided by your telephone company.
When configuring the technology, the first step is installing these two necessary hardware components. The TA connects the ISDN line to the user's equipment using the appropriate cables. Once the hardware is set up, the next step is activating the line with your Internet service provider.
When you contact the ISP, you'll likely need to provide them with certain details, like the line number and the desired service configuration. Upon activation, the service provider will assign the required resources.
ISDN uses various protocols to establish connections. You're required to determine which protocols you will use over the ISDN line. The most common protocols include PPP (Point-to-Point Protocol), HDLC (High-Level Data Link Control), and ISDN D-channel protocols.
Next, configure the specific services that will be used over the ISDN line. This can include voice calls, Internet access, and so on. Finally, test the connection and verify that all desired services function correctly.
Advantages of ISDN
There are many advantages to using Integrated Services Digital Network technology. Consider them below.
- Reliable connection. Integrated Services Digital Network utilizes digital signals, which are less susceptible to interference compared to analog signals. You can expect fewer dropped calls, clearer audio, and more stable data transmission.
- Multiple digital channels. Unlike traditional phone lines that can only handle one call at a time, ISDN offers multiple channels. Users can make and receive multiple calls simultaneously.
- Faster data transfer rate. It offers significantly faster data transfer rates, ranging from 64 Kbps to 128 Kbps per channel.
- Efficient use of bandwidth. ISDN channels are allocated only when in use. This allows for more efficient use of bandwidth resources.
- Improved call quality. Due to the digital nature of the signal, ISDN provides quality voice. This is especially noticeable during long-distance calls or when using features like speakerphone.
- Greater flexibility. The technology offers a wide range of functionalities. Users can benefit from features like call forwarding, caller ID, voicemail, and conferencing capabilities.
- Integrated services. It allows for the integration of voice, data, and other communication services like fax and video over a single line. This eliminates the need for separate lines for different services, potentially reducing overall costs.
Disadvantages of ISDN
Though using Integrated Services Digital Network as a communication method has its benefits, there are some disadvantages to consider as well.
- Associated costs. Setting up ISDN includes specialized equipment like ISDN lines, which are costly. Service providers often charge higher monthly subscription fees as well.
- Limited coverage. This technology isn't as widely available as newer options like cable or fiber. This means it might not be accessible in all regions or remote areas.
- Obsolescence. Nowadays, many consider ISDN Internet services outdated compared to newer, more advanced options like fiber optic or cable Internet.
- Limited features. It offers a limited set of features compared to modern broadband options. While it provides voice and data connectivity, it lacks the high-speed capabilities required for activities like streaming high-definition video.
ISDN services
ISDN networks provide digital services to users. These telecommunication services are divided into three categories: bearer services, tele-services, and supplementary services.
Bearer services
Bearer services facilitate the exchange of data between users without the network manipulating the material. These services operate at the first three layers of the OSI model - the physical layer, the data link layer, and the network layer.
The ISDN standard defines these bearer services in detail, outlining how they should operate within the network.
You can implement these services using various network technologies, including circuit-switched, packet-switched, frame-relay, or cell-relay networks.
Tele-services
Tele-services in ISDN offer functionalities beyond simply transporting data. They operate at higher layers of the OSI model. These services depend on the capabilities of bearer services for basic transmission.
Users don't necessarily need to know the intricate details of how these services are processed within the network. While ISDN outlines these services, they have not yet become standardized across all ISDN networks.
Some examples of teleservices are telephone, telefax, and teleconferencing.
Supplementary services
Supplementary services offer extra capabilities beyond basic phone services. These services enhance the overall communication experience by providing additional functions to both the bearer services and the tele-services.
Examples of supplementary services include reverse charging, call waiting, and message handling. These are all commonly used features offered by modern telecommunication providers.
The future of ISDN
ISDN, once a popular choice for digital communication, is facing a diminishing role in the evolving landscape of technology.
The rise of newer, more advanced technologies like fiber optic and high-speed broadband has significantly impacted the relevance of ISDN.
These newer options offer greater bandwidth, faster speeds, and often, lower costs. As a result, many telecommunications providers have chosen to phase out ISDN services in favor of these more efficient alternatives.
While ISDN may not be as widely used for general communication needs anymore, it still holds value in specific niche applications.
Frequently asked questions
Why is ISDN being phased out?
Integrated Services Digital Network still relies on older infrastructure that struggles to keep pace with the demands of today's digital world. Newer technologies, like fiber optic, offer more advanced functionalities.
Is ISDN being replaced by Voice over Internet Protocol?
Yes, VoIP technology has largely replaced Integrated Services Digital Network for many organizations. VoIP offers better voice quality and unified communications.
Is Integrated Services Digital Network more secure than traditional phone lines?
Yes. Since Integrated Services Digital Network uses digital signals, it's less susceptible to eavesdropping.
What's the difference between ISDN and DSL?
The main difference between Integrated Services Digital Network and Digital Subscriber Line is the speed of data transmission. DSL transmits data faster because ISDN is a dial-up service that goes through a singular line. Integrated Services Digital Network also requires multiple adapters, though both use copper wires for transmission.