PSTN: The Traditional Telephone System

PSTN is the old telephone system. It is also known as the Plain Old Telephone System or POTS. This network carries voice calls for calls made from landlines or cell phones. PSTN refers to the global network of voice carrying telephone infrastructure. The commercialisation of telephones began around 1876. The demand for the service led to the growth of the PSTN and also deployment of tele-traffic engineering and the necessity to maintain Quality of Service (QoS).

The components that Public Switched Telephone Network include are telephone lines, fibre optic cables, switching centres, cellular networks, satellites and cable systems. While on the front, one simply dials a number and on the other end, one receives the call, the backend process is much more complicated than this. There are numerous steps working behind the call, which makes it possible and eventually successful.

Working of PSTN system

• Firstly, the telephone set converts the sound waves into electrical signals. Thereafter, transmission of these signals to a terminal takes place through a cable. The function of the terminal is to collect the electrical signals and transmit this to the central office (CO).
• The central office routes the calls through fibre optic cable in the form of electrical signals. The fibre optic cable carries the signals in the form of light pulses to their final destination. The purpose of tandem and central office is call routing. After reaching the right office, on the receiving end, the light pulses change back to electric signals.
• Next, the electrical signals are routed to a terminal. Thereafter, the terminal routes the call to the appropriate telephone number.
• Eventually, when it is for the user to receive the call, the telephone set converts the electrical signal back to sound waves which the receiver hears.

Comparing PSTN and VoIP

• Cost: In terms of cost, VoIP is way ahead of PSTN. While PSTN requires dedicated lines and hardware, VoIP requires minimal hardware apart from a telephone set or a mobile device.
• Productivity: VoIP usage in enterprises have shown an increase in productivity. Due to several features and higher speed, VoIP performs better than PSTN in this aspect.
• Security: While it appears that PSTN might offer better security than VoIP, it is partially correct. Though previously in initial stage VoIP did face security issues, in the present day, things are much better. There are encryptions, 2-factor authentication, several passwords and other methods to keep things secure.
• Maintenance: With numerous hardware, telephone lines and all other accessories, the maintenance of Public Switched Telephone Network is a costly affair. On the other hand, VoIP Technology is based on software and requires minimum maintenance.

To know more about PSTN and VoIP check here.