Difference Between ISDN and PSTN

ISDN and PSTN are both communication protocols used for voice and data transmission over traditional telephone networks. However, there are some differences between ISDN and PSTN.

ISDN, or Integrated Services Digital Network, is a digital communication system that allows speech and data to be transmitted over existing phone lines. PSTN, or Public Switched Telephone Network, is a traditional analogue communication technology that uses copper lines to transfer voice signals.

Read this article to find out more about ISDN and PSTN and how they are different from each other.

What is ISDN?

ISDN, or Integrated Services Digital Network, is a digital communication system that allows speech and data to be transmitted over existing phone lines. When compared to the PSTN, it provides faster data transfer rates and higher call quality. ISDN also supports multiple simultaneous connections, allowing numerous users to use the same line at the same time. ISDN is therefore suitable for businesses that demand high-speed data transfer and reliable voice communication.

ISDN has a number of advantages over classic analogue communication protocols such as PSTN. ISDN has the advantage of using digital signalling, which allows for faster call setup times and fewer errors as compared to the analogue signalling used by the PSTN. ISDN can allow data transfer speeds of up to 128 kbps, which is significantly higher than PSTN's maximum speed of 56 kbps. As a result, ISDN is more suitable for businesses that require high-speed data transfers.

ISDN also supports multiple simultaneous connections, allowing numerous users to use the same line at the same time. This is achieved by dividing the ISDN line into two or more channels, each of which can deliver voice or data. ISDN can support up to 30 channels in Europe and up to 23 channels in the United States.

ISDN services are classified into two types: basic rate interface (BRI) and primary rate interface (PRI). BRI is designed for home and small business use, with two 64 Kbps B-channels for data and voice transmission and a 16 Kbps D- channel for signaling and control. PRI is designed for larger businesses and consists of 23 B-channels and one D-channel at 64 kbps.

ISDN additionally supports a number of extra services, including caller ID, call forwarding, call waiting, and three-way calling. ISDN becomes a more versatile and useful communication technology for corporations and other users as a result of these features.

Overall, ISDN is a digital communication technology that provides faster data transfer rates, higher call quality, and many simultaneous connections when compared to traditional analogue communication protocols such as PSTN. Because of its versatility and the features, it offers, it is suitable for a wide range of users, from small businesses to major corporations.

What is PSTN?

PSTN (Public Switched Telephone Network) is a traditional analogue communication technology used to transfer speech signals through copper cables. PSTN is the most frequently used communication protocol in the world.

The PSTN is a complex network of telecommunication switches, transmission lines, and other equipment that is used to transfer voice and fax signals over long distances. The PSTN transfers electrical signals across copper wires by converting sound waves. At the receiver's end, these electrical signals are transformed back into sound waves.

The public switched telephone network (PSTN) only provides basic voice communication services and has limited data transmission capabilities. It normally offers data transfer rates of up to 56 kbps, which is significantly slower than the highest speed of ISDN, which is 128 kbps. PSTN uses analogue signalling, which is more prone to errors and requires longer call setup times than ISDN's digital signaling.

The PSTN provides various services that are common in many home and small business phone systems, such as call waiting, call forwarding, caller ID, and three-way calling. These characteristics, however, are limited in scope and functionality as compared to ISDN.

Despite its drawbacks, PSTN is still commonly used because it is simple, dependable, and readily available. It is suitable for home users and small businesses in need of basic voice communication services. PSTN also offers a low barrier to entry, making it available to customers who cannot afford more expensive digital communication protocols such as ISDN.

In recent years, other communication technologies such as VoIP (Voice over Internet Protocol) and cellphone networks have mostly replaced the PSTN. However, PSTN is still widely used in many parts of the world, particularly in rural areas where digital communication infrastructure is limited.

Difference between ISDN and PSTN

The following table highlights the major differences between ISDN and PSTN −

Characteristics	ISDN	PSTN
Transmission protocol	Digital	Analog
Data transfer rates	Up to 128 Kbps	Up to 56 Kbps
Call setup time	Faster	Slower
Signal quality	Better	Lower
Number of channels	Up to 30 in Europe, 23 in the US	1
Simultaneous connections	Multiple	One
Caller ID	Yes	Yes
Call forwarding	Yes	Yes
Call waiting	Yes	Yes
Three-way calling	Yes	Yes
Cost	High	Low
Availability	Limited in some areas	Widely available
Suitable for	It is appropriate for businesses that require high-speed data transfer.	It is suitable for residential users and provides basic voice communication services.

Conclusion

In conclusion, the primary difference between ISDN and PSTN is that ISDN is a digital communication technology that allows for faster data transfer rates, higher call quality, and numerous simultaneous connections. It is more suitable for businesses that require fast data transfers and a consistent voice connection.

PSTN is a traditional analogue communication protocol with limited data transmission capabilities that provides basic voice communication services. It is more suitable for home users and small businesses that only need basic voice communication services. The decision between ISDN and PSTN depends on the user's specific needs and requirements, as well as the availability of communication infrastructure in their area.