Pstn

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PSTN

Definition:

PSTN stands for Public Switch Telephone Network, which is defined as the Global collection of interconnects. It was originally designed to support circuit-switched voice communication. The PSTN provides the traditional Plain Old Telephone Service (POTS) to residences and many other establishments.

PSTN, which used to be only a network of fixed-line analog telephone systems, is now almost completely digital. Most of its subscribers are still linked by analog circuits. Fixed-line and mobile phones are now included in this new system set-up.

figure [1]

Bandwidth:
The basic PSTN network link supports 64 Kbps of bandwidth. The PSTN phone line which carries this bandwidth is basically a copper cable. The PSTN utilizes the SS7 (Signalling System#7) signaling protocol. There are the parts of the PSTN which is utilized for DSL, VoIP and other Internet-based network technologies. PSTN Standard:

The PSTN is created by the ITU-T which is basically a technical standard. It uses E.163/E.164 telephone numbers for addressing. Architecture :
Traffic engineering was the earliest example of “PSTN” that delivers the quality of service (QoS) guarantees. The PSTN Architecture is shown below:

Figure [2]

PSTN traces its beginnings to the invention of the telephone and the early development of the telephone service. The first telephones were all in private use and had no networks as they were wired in pairs. Employing the same technology used by telegraph systems, every telephone was later connected to a local telephone exchange all wired together with trunks. These networks were in turn wired together in a hierarchy that spans cities, countries, continents, and oceans. A network was created using analog voice connections using manual switchboards. They were replaced by automated telephone exchanges, and later on by digital switch technologies. Nearly all switches now employ digital circuits among exchanges, whilst two-wire analog circuits are...
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