What is the difference between P.S.T.N and I.S.D.N?

PSTN stands for Public Switched Telephone Network. ISDN stands for Integrated Services Digital Network.

These are two distinct networks that work to transfer voice and data over the phone lines.

Public Switched Telephone Network

The public switched telephone network is a traditional circuit-switched telephone network. It has been around for a very long time, even before the commercialization of the telephone network around 1874.

It consists of the complex interconnection of switching centers and end-users that offers a voice connection between any two valid subscribers.

A successful connection to the public switched telephone network needs an operator and a pair of wires, typically overheadRunning from each subscriber to the exchange where these are terminated at a switchboard. It also needs a telephone exchangeAutomatic exchange basically composed of switches.

As the number of subscribers increases, the demand for physical space to house the switchboards and operators also increases. This led to massive exchange buildings and a large staff required to operate the PSTN system when it came into existence.