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What is PSTN? (Public Switched Telephone Network)

Public Switched Telephone Network


The PSTN, Public Switched Telephone Network, was the first to emerge.

The PSTN is a public-facing telephone network (as opposed to an intra-enterprise or industry-specific network) through which we all make calls almost every day in our daily lives.

Nowadays the PSTN is a generic term for the operator's telephone network, even though nowadays the operator's telephone network is progressively based on VoIP technology, more specifically the PSTN is known as IMS, VoLTE, etc.

The definition of the PSTN when it emerged was a public telephone network based on circuit-switched technology. It was made up of circuit-switched voice exchanges and fixed-line terminals.

In contrast to the later emergence of ISDN (digital network), the PSTN is also generally referred to as an analog telephone network. However, the core of the later PSTN - the switch and the circuit trunk (Trunk) that connects the switch - is completely digital.

Of course it is correct to call the PSTN an analog telephone network because its terminals, and the connections between the switches and the terminals, the so-called last mile, are based on analog technology and are designed specifically for voice services.

The PSTN can only carry one service, telephony (which is what it was originally designed for, although dial-up internet access via modem is also possible, but it is very costly, extremely inefficient and affects the reception of calls), and as the demand for data communication increases, it gradually no longer meets the demands placed on the operator's network.

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