PSTN

What is PSTN？

PSTN (Public Switched Telephone Network) refers to the traditional circuit-switched telephone network, primarily used for voice communication. It is also known as Plain Old Telephone Service (POTS). PSTN provides the infrastructure and services for wired telephone systems, enabling voice calls through the establishment of a dedicated point-to-point connection. The PSTN network is composed of terminal equipment (such as landline phones), local and long-distance switching offices, and various signaling systems, which allow voice and other forms of communication to be transmitted via twisted copper wires, fiber optic cables, and other media, with a wide range of applicability.

In addition, the PSTN has high reliability and stability, and was once the primary choice for home and business communications. However, with the development of the Internet and digital technologies, the PSTN faces growing challenges, especially in terms of bandwidth, functionality and cost-effectiveness. Nevertheless, the historical significance and technical underpinning of the PSTN have provided a solid foundation for the evolution of modern communications.

How PSTN Works？

PSTN (Public Switched Telephone Network) primarily operates based on circuit-switched technology, delivering voice communication services through a series of complex hardware and software components. These components include user terminal devices, switching centers, transmission media, and transport networks.

In simple terms, at the user device end, PSTN converts your voice into electrical signals, which are transmitted to a switching center. The switching center then directs the user's call signal to the target terminal, and the destination terminal translates the signal back into sound, allowing the call to reach the corresponding phone number. During this process, signals are transmitted via copper wires, fiber optics, and satellite networks. Once the call is answered, the digital signals are converted back into voice, enabling real-time communication.

The working process of PSTN involves several components and steps, from user dialing, signaling processing, switching and routing, to establishing and ending the communication. The entire process relies on circuit-switched technology, ensuring a stable and high-quality voice connection during the call.

PSTN vs VoIP

While PSTN has been the dominant technology for voice communication for a long time, IP-based network communication is gradually replacing PSTN as digital information technologies evolve. PSTN is scheduled for a phased retirement by 2030 in most countries, meaning that traditional landlines will no longer be in use. Thus, the transition from PSTN to VoIP has become an inevitable choice for businesses.

PSTN (Public Switched Telephone Network) and VoIP (Voice over Internet Protocol) are two distinct telecommunication methods, and they differ significantly in terms of working principles, transmission methods, costs, and functionality. Below is a key comparison between the two:

Conclusion

PSTN, as a fundamental communication technology, has undergone a long journey from its inception in the late 19th century to becoming the backbone of global voice communication in the 20th century. Its development has marked significant milestones, from the invention of the automatic switch to the introduction of digital switching and fiber optic technology. However, with the emergence of IP-based technologies and the increasing dominance of VoIP, the traditional circuit-switched model is gradually being phased out.

The historical contributions of PSTN cannot be overlooked, but the advantages of VoIP will lead communication into a new digital era. The growing demand for flexible, cost-effective, and scalable communication solutions has driven the gradual integration of PSTN with the internet and IP (Internet Protocol) technologies, enabling interoperability between traditional telephone services and IP telephony (VoIP). Many businesses are opting for hybrid communication systems, and this incremental migration strategy avoids large-scale investments and technical risks all at once, allowing companies to gradually transition from PSTN to VoIP and upgrade their communication infrastructure according to their needs and budgets.