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What is Public Switched Telephone Network?
Originally built using analogue copper wires, switchboards and exchanges, PSTN allowed users to make voice calls by establishing a dedicated physical circuit between two endpoints for the duration of the call. This guaranteed consistent call quality and reliability for both consumer and business phone lines, which is why it became the foundation of global telecommunications.
How does PSTN work?
PSTN operates using circuit switching. When you make a call from a landline, the network creates a direct path through a series of exchanges and switches to the recipient. That circuit remains open for the entire conversation, even if no one is speaking.
The network consists of:
Local exchanges that connect homes and businesses
Regional and national switching centres
International gateways
Copper cabling infrastructure
Over time, parts of PSTN evolved to use digital switching technology, improving efficiency and call clarity. However, the underlying infrastructure in many areas still relies heavily on copper lines.
Why is PSTN being phased out?
While PSTN has been incredibly reliable, it was designed purely for phone lines. Modern businesses require far more bandwidth to support internet access, cloud services, video conferencing and unified communications.
Maintaining copper-based infrastructure is expensive and less energy efficient than modern fibre networks. As a result, many countries, including the UK, are phasing out PSTN services through the analogue switch off in favour of digital alternatives such as VoIP and full fibre broadband.
The move away from PSTN is part of a wider digital transformation of national telecoms infrastructure. Businesses that still rely on traditional business phone lines must plan their transition to IP-based communication systems to avoid disruption.
PSTN vs modern communication
Unlike PSTN, modern communication systems use packet switching. Voice calls are converted into digital data and transmitted over internet connections. This allows greater flexibility, scalability and cost efficiency.
Although PSTN laid the groundwork for global voice communication, it cannot compete with the speed, flexibility and integration offered by today’s digital networks.
