Communication: telegraph and telephone to optical fibre and submarine cables

Detail

1. What communication means

• Communication means sending words, messages, facts and ideas from one person or place to another.
• Writing let people keep messages, but tied them to transport.
• A written message had to be carried by hand, by animal, by boat, by road, by rail or by air.
• So a message could travel only as fast as the vehicle that carried it.

• This is why transport routes are called "lines of communication".

• Mobile phones and satellites have separated communication from transport.

• A message now travels as an electric or radio signal, not on a vehicle.
• Post offices still carry huge amounts of mail, so the old link has not fully gone.

2. Telegraph and telephone

• Telegraph: sends coded electric signals along a wire. Operators tapped Morse code (letters written as short and long pulses, "dots and dashes").

• The telegraph helped settle (colonise) the American West. Settlers, railways and governments could keep in touch across long distances.

• The first telegraph cables under the sea:

• 1858: the first transatlantic telegraph cable was laid. It carried fewer than 750 messages and failed after about three weeks [9].
• 16 August 1858: Queen Victoria sent the first message to US President James Buchanan. It took more than 16 hours to transmit [10].
• 1866: the first cable that worked for a long time was laid between Ireland and Newfoundland (Canada) across the North Atlantic [9].

• Period link: this is the same age as the Suez Canal (1869) and the trans-continental railways. Steam routes moved goods, and cables moved news and orders, so empires and trading firms became more closely linked.

• Telephone: carries the human voice as an electric signal.

• AT&T (American Telephone and Telegraph Company) had a monopoly on US telephones in the early and mid-20th century. A monopoly means one company controls the whole market.

• The telephone helped US cities grow.

  • Firms could manage everything from one head office in a big city.
  • They ran branch offices in small towns and gave orders by phone.
  • Head-office jobs gathered in the cities, and the cities grew.

• The telephone is still the most used mode of communication.

• Satellite-enabled cell phones connect villages in developing countries, where laying wires is costly.

3. Telecommunication

• Telecommunication means communication over long distances by electronic means, such as telegraph, telephone, radio, satellite and the internet.
• It made communication much faster:
• Letters carried by ship or rail took weeks.
• Telegraph and telephone cut this to minutes.

• Mobile telephony made it instant and possible from almost anywhere.

• The telegraph, Morse code and telex (a network of teleprinters that sent typed messages over phone lines) are now almost obsolete.

4. Mass media

• Mass media are channels that reach very large audiences at the same time.
• Radio, television and newspapers bring news, pictures and entertainment to millions of people. They are vital for advertising.
• The internet and social media are now the fastest-growing mass media.

Medium	Signal or carrier	Main strength
Newspaper	Printed paper carried by road or rail	Detailed news, a lasting record
Radio	Radio waves	Reaches remote areas; cheap; works without reading skills
Television	Radio waves, cable or satellite	Pictures and sound; strong for advertising
Internet and social media	OFC, mobile and satellite links	Two-way and instant; growing the fastest

5. Optical fibre cable (OFC)

• Optical fibre cable (OFC): thin threads of glass that carry data as pulses of light.
• It was the first breakthrough of the digital age. Telephone companies replaced copper wire with OFC.

Feature	Copper wire	Optical fibre
Signal	Electric current	Light pulses
Amount of data	Small	Very large
Speed	Slower	Very fast
Security	Easy to tap	Hard to tap
Errors	Affected by electrical interference	Almost error-free

• How the internet was born:
• In the 1990s, information became digital (stored and sent as 0s and 1s).
• Telecommunication and computers could now use the same digital signal.
• The two merged to form the internet.

6. Submarine communication cables: the world's data network

• Submarine communication cable: a fibre-optic cable laid on the seabed to carry data between countries and continents.
• Share of traffic: about 99% of international internet traffic goes through submarine cables (UN, 2026). Older estimates put it at 95% or more [8].
• Size of the network (2026): over 500 commercial cables, about 1.7 million km long in total. They carry hundreds of terabits of data every second [8].
• Cables were designed to last about 25 years. Cable capacity has grown by about 40% a year over the past 40 years [8].
• Satellites vs cables: satellites cover remote places and ships. Cables carry much more data at lower delay (latency), so most global traffic stays on the seabed.

7. India's landing stations and island cables

• A cable landing station (CLS) is the place on the shore where a submarine cable comes out of the sea and joins the land network.

• India's main hubs are Mumbai (Arabian Sea coast, Maharashtra), Chennai (Bay of Bengal coast, Tamil Nadu) and Kochi (Arabian Sea coast, Kerala).

• Chennai–Andaman & Nicobar Islands (CANI) cable:

• Inaugurated in August 2020. It is about 2,313 km long and runs across the Bay of Bengal [2].
• It connects Port Blair and seven other islands: Little Andaman, Car Nicobar, Kamorta, Great Nicobar, Havelock, Long Island and Rangat [2].

• It has four fibre pairs. Each pair can carry up to 6.4 Tbps (terabits per second) with very low delay [3].

• Kochi–Lakshadweep Islands (KLI-SOFC) cable:

• Inaugurated at Kavaratti on 3 January 2024. It is 1,868 km long and runs across the Arabian Sea. It cost ₹1,072 crore plus taxes [4].
• It reaches 11 islands: Kavaratti, Agatti, Amini, Kadmat, Chetlet, Kalpeni, Minicoy, Androth, Kiltan, Bangaram and Bitra [4].

• It gives about 100 times faster internet than the earlier satellite links [4].

• Why the island cables matter: they bring e-governance, telemedicine, online education, banking and tourism. They also tie strategic island chains near the sea lanes more closely to the mainland.

8. Risks to submarine cables

• How often cables break: there are usually 150–200 cable incidents a year, or about 3–4 a week [8].
• Main causes:
• About 80% are caused by human activity: ship anchors dragged along the seabed and fishing trawlers (boats pulling heavy nets along the bottom) [8].

• The rest come from natural hazards, such as earthquakes, undersea landslides and volcanic eruptions. Example: Tonga has had three major cuts since 2019 [8].

• Chokepoints: these are narrow sea passages where many cables bunch together, so one accident can cut several at once.

• Red Sea, 2024: cable cuts disrupted an estimated 25% of data traffic between Europe and Asia [8].

• The cables there pass through the Bab-el-Mandeb strait and the Suez route, the same corridor used by ships.

• Sabotage: there have been suspected deliberate cuts of cables in the Baltic Sea.

• Too few repair ships: repairing a cable means a specialised ship must find the break, lift the cable, splice in a new piece and lay it back. Few such ships exist, so repairs can take weeks.
• Responses:
• India — TRAI recommendations, June 2023 [5]:
  • study ways to fund Indian-flagged cable repair ships, including government incentives;
  • set up cable depots on both the west and east coasts to store spare cable and repair equipment;
  • create two categories of landing station: Main CLS and CLS Point of Presence (CLS-PoP);
  • suggest that coastal states offer incentives for new landing stations, and waive Right-of-Way (RoW) charges for OFC links to them.
• India — data centres: capacity grew from 375 MW in 2020 to more than 1,500 MW [6]. More data centres need more cable landings (see tertiary-quaternary-activities).
• Global: the ITU (International Telecommunication Union) and the ICPC (International Cable Protection Committee) formed the International Advisory Body for Submarine Cable Resilience. It has 42 members. Its first meeting was on 12 December 2024, followed by a summit in Abuja, Nigeria, in February 2025 [7].

Prelims Hooks

• "Lines of communication" is the name for transport routes, because written messages once had to travel on vehicles.
• AT&T had the US telephone monopoly in the early and mid-20th century. The telegraph is linked to settling the American West.
• First lasting transatlantic cable (1866): Ireland to Newfoundland. The 1858 cable failed after about three weeks [9].
• OFC carries data as light pulses, not electric current. It is fast, secure and almost error-free.
• Submarine cables carry about 99% of international internet traffic, not satellites [8].
• CANI (Chennai–Port Blair, Bay of Bengal, 2020, about 2,313 km) vs KLI-SOFC (Kochi–Kavaratti, Arabian Sea, 2024, 1,868 km, 11 islands) [2][4].
• Main cause of cable faults: human activity (anchors and fishing), about 80%. Natural hazards cause fewer [8].
• Red Sea cuts (2024) disrupted about 25% of Europe–Asia data traffic [8].
• The International Advisory Body for Submarine Cable Resilience was formed by ITU and ICPC in 2024 [7].
• Trap: telex, Morse code and telegraph are almost obsolete, but the telephone is still the most used mode.

Mains Points

• Communication no longer depends on transport. Telegraph → telephone → OFC → mobile and internet. This shrank distance, helped cities grow (head offices in cities, branches in towns) and made services trade and the quaternary sector possible (GS-I: distribution of service industries).
• Submarine cables are critical infrastructure. About 99% of data runs through 500+ cables. They gather at chokepoints like the Red Sea and Bab-el-Mandeb, and face anchors, trawlers, earthquakes and sabotage. So cable security is now part of geopolitics and maritime security (GS-III) [8].
• India's response: island cables (CANI 2020, KLI-SOFC 2024) bridge the digital divide and strengthen strategic islands. TRAI's 2023 plan proposes Indian repair ships, cable depots on both coasts and easier CLS rules. Data-centre growth (375 MW to more than 1,500 MW) needs more landing stations on both coasts to avoid depending on Mumbai and Chennai [2][4][5][6].
• Building resilience: spread out cable routes (east and west coasts, more landing points), add more repair ships, and work with other countries (ITU–ICPC Advisory Body, 2024). This lowers the risk that one cut stops a region's economy [7].