STD, ISD, and PCO are common terms used in the telecommunication industry. While most of us are familiar with these terms, not many of us know their full forms. In this article, we will discuss the full form of STD, ISD, and PCO, and their significance.

STD

STD stands for Subscriber Trunk Dialling. It is a telephone system that enables long-distance calls to be made without the need for operator assistance. STD was first introduced in the United Kingdom in 1958, and it quickly became popular in other countries as well. Today, STD is available in almost all countries around the world.

STD works by assigning a code to each telephone exchange in a particular area. When a call is made to a long-distance number, the caller dials the STD code followed by the area code and the telephone number. The call is then routed through the appropriate telephone exchange to the destination number.

ISD

ISD stands for International Subscriber Dialling. It is a telephone system that enables long-distance calls to be made between different countries. ISD was first introduced in 1960, and it has since become an essential part of international communication.

ISD works by assigning a code to each country. When a call is made to an international number, the caller dials the ISD code followed by the country code and the telephone number. The call is then routed through the appropriate international exchange to the destination number.

PCO

PCO stands for Public Call Office. It is a public telephone booth that allows people to make calls without having a telephone connection at home. PCOs are widespread in India and other developing countries, where many people do not have access to telephones.

PCOs work by using a coin-operated system. The caller inserts a coin into the machine and dials the number they wish to call. The call is then connected, and the caller can talk for a specified period, depending on the amount of the coin inserted.

Conclusion

In conclusion, STD, ISD, and PCO are three common terms used in the telecommunication industry. STD enables long-distance calls to be made within a country, ISD enables long-distance calls to be made between different countries, and PCO allows people without access to telephones to make calls from public telephone booths. Knowing the full forms of these terms can help you better understand how the telecommunication industry works.

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