Home Resource Centre What Is PSTN Network? How It Works; Key Features; PSTN vs VoIP

Table of content:

What is PSTN in Computer Networks?
How PSTN Works
Components of PSTN
Advantages and Disadvantages of PSTN
Comparison of PSTN and VoIP
Applications of PSTN
Transition from PSTN to IP-Based Systems
Frequently Asked Questions (FAQs)

What Is PSTN Network? How It Works; Key Features; PSTN vs VoIP

Despite the emergence of newer technologies like VoIP (Voice over IP) and mobile networks, PSTN remains an essential part of telecommunication systems worldwide.

5 mins read

What Is PSTN Network? How It Works; Key Features; PSTN vs VoIP

The Public Switched Telephone Network (PSTN) is a global network for voice communication that primarily uses copper telephone lines, fiber optics, microwave transmission, and cellular networks. PSTN operates as a circuit-switched network, meaning a dedicated connection is established between parties during a call, allowing for clear and reliable voice transmission.

What is PSTN in Computer Networks?

In the context of computer networks, PSTN is the traditional voice communication network, but it also serves as a foundation for data transmission in areas lacking advanced digital infrastructure. While it is largely known for voice communication, PSTN is often used in conjunction with computer networks to transmit low-speed data, such as for dial-up internet connections and fax services.

PSTN Full Form in Computer

PSTN stands for Public Switched Telephone Network in computer networking and telecommunications.

How PSTN Works

PSTN operates on a circuit-switching model. When a call is made, a dedicated channel is created between the caller and the recipient for the duration of the call. Here's a simplified step-by-step explanation of how PSTN works:

Dialing: The caller dials the number of the recipient, which sends a signal to the local exchange.
Call Routing: The exchange routes the call through a series of interconnected switching centers to locate the recipient.
Circuit Establishment: Once the connection is found, a dedicated circuit is established for the call.
Data Transmission: Voice signals are converted to electrical signals and transmitted across the established circuit.
Circuit Release: When the call ends, the circuit is released and made available for new calls.

Components of PSTN

The main components of the PSTN network include:

Component	Description
Subscriber Lines	Connections between users' devices and the local exchange.
Switching Centers	Central points that manage and route calls through the network.
Transmission Media	Copper wires, fiber optics, and microwave links that carry the voice signals.
Signaling System	Protocols used to establish and control calls. Commonly SS7 (Signaling System No. 7)
Control Centers	Centers that manage the overall network and ensure reliability.

Advantages and Disadvantages of PSTN

Advantages of PSTN

Reliability: PSTN provides a dedicated and stable connection for voice calls, ensuring high-quality service.
Wide Coverage: PSTN is available almost everywhere, even in remote and rural areas.
Security: Circuit-switched networks provide secure communication lines compared to packet-switched networks.

Disadvantages of PSTN

Limited Bandwidth: PSTN has limited data capacity, making it less efficient for high-speed data transmission.
Costly Infrastructure: Maintaining PSTN infrastructure is costly, especially with the transition to IP-based systems.
Slow Adaptation to Modern Needs: PSTN is not optimized for modern data-heavy communication, such as video calling.

Comparison of PSTN and VoIP

As newer technologies like VoIP emerge, it is helpful to understand how PSTN differs from these alternatives.

Feature	PSTN	VoIP
Technology	Circuit-switched	Packet-switched (Internet Protocol)
Cost	Typically higher for long-distance	Generally lower, especially for long-distance
Reliability	Highly reliable	Dependent on internet quality
Data Types	Voice only (mainly)	Voice, video, and multimedia
Scalability	Limited scalability	Highly scalable

Applications of PSTN

PSTN is used for several communication applications, primarily in voice communication and low-speed data transfer:

Landline Telephony: Standard voice calls across landline phones.
Dial-Up Internet: PSTN was originally used for dial-up internet access before broadband became widely available.
Fax Communication: Many businesses use PSTN for fax transmissions.
Emergency Services: PSTN networks are commonly used for emergency communication systems due to their reliability.

Transition from PSTN to IP-Based Systems

The rise of IP-based networks and broadband internet has led to a decline in PSTN usage. Many telecommunications providers are transitioning to digital IP systems, such as VoIP, which are more cost-effective and support modern communication needs like video calling, file sharing, and multimedia messaging.

Reasons for Transition

Cost Efficiency: IP networks are cheaper to install and maintain than PSTN infrastructure.
Flexibility: IP-based systems offer more features, including multimedia support.
Integration: Digital networks can integrate with other modern communication systems, providing a unified experience.

Frequently Asked Questions (FAQs)

What is the PSTN network?

The Public Switched Telephone Network (PSTN) is a global voice communication network that uses circuit-switching technology.

How does PSTN work?

PSTN establishes a dedicated connection between two parties for the duration of a call, allowing voice signals to be transmitted over copper, fiber, or microwave transmission.

What are the main components of PSTN?

PSTN includes subscriber lines, switching centers, transmission media, signaling systems, and control centers.

What is circuit switching in PSTN?

Circuit switching is a method where a dedicated communication path is established between the caller and the recipient during a call.

What are the advantages of PSTN?

PSTN offers reliable, secure, and widely available voice communication with high-quality call connections.

What are the limitations of PSTN?

PSTN has limited data transmission capacity, high maintenance costs, and lacks support for modern multimedia communications.

How does PSTN compare to VoIP?

PSTN is circuit-switched and optimized for voice calls, while VoIP uses packet-switching, supports multimedia, and is generally more cost-effective.

Is PSTN still used today?

Yes, although it is declining, PSTN is still in use, particularly in areas without high-speed internet access.

What is SS7 in PSTN?

SS7 (Signaling System No. 7) is a protocol used in PSTN for call setup, control, and teardown.

Why are companies switching from PSTN to IP-based systems?

IP-based systems are more affordable, scalable, and capable of handling modern data-heavy communication requirements.

To err is human, and while we have put our best effort into ensuring this content is accurate and helpful, there is always room for improvement! If you spot any errors or think of ways to make this article even better, please feel free to reach out. Your feedback is invaluable, and we are always happy to learn from you. Thank you for reading!

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Edited by

Shivangi Vatsal

Sr. Associate Content Strategist @Unstop

I am a storyteller by nature. At Unstop, I tell stories ripe with promise and inspiration, and in life, I voice out the stories of our four-legged furry friends. Providing a prospect of a good life filled with equal opportunities to students and our pawsome buddies helps me sleep better at night. And for those rainy evenings, I turn to my colors.