Three major undersea cables -- the Sea Me We 4, Sea Me We3, and FLAG -- were cut, considerably slowing down India's internet and voice traffic. The extent of the damage is still being assessed.

The voice operations (call centres) of IT-BPO firms comprise around 20-30 per cent of most firms in India, and get hit the most -- especially if the International Private Leased Circuits (IPLCs) are down too. An IPLC is a point-to-point private line used by an organisation to communicate between offices that are dispersed throughout the world.

Consequently, it's generally the smaller business process outsourcing (BPO) units that get badly affected. The larger ones have built-in redundancy that does not make them very vulnerable. They also have connections from both the Pacific and Atlantic routes so if one route is affected the load automatically gets transferred on the other route.

Moreover, those firms that have delivery centres around the world will not be affected as much since they can divert some work to other centres. Moreover, a considerable amount of high-end analytics work can be done offline.

Fibres cut in recent years:

• January 20, 2007: Due to Taiwan Earthquake
• January 30, 2008: In Mediterranean Region
• Now December 19, 2008: Again in Mediterranean Region

"Being a Saturday, we may not feel the full impact of the cuts. Though there's no doubt that traffic has slowed down to a snail's pace. Moreover, given the global slowdown, most companies themselves are going slow, and hence the impact may be lower. However, what is surprising is the regularity with which these cuts have been happening," said Rajesh Chharia President, Internet Service Providers Association of India (ISPAI), told Business Standard.

A statement from France Telecom said the Sea Me We4 could be up by December 25, and it hoped the overall situation would be back to normal by the end of December. The causes of the cut -- located in the Mediterranean between Sicily and Tunisia, on sections linking Sicily to Egypt -- remain unclear.

France Telecom said it immediately alerted one of the two maintenance boats based in the Mediterranean area, the "Raymond Croze". In its initial assessment, the company listed 14 countries affected by the current problem.

The Maldives are 100 per cent down, followed by India, which has 82 per cent disruption. Qatar, Djibouti and the UAE were the next most widely affected areas with about 70 per cent service interrupted. Disruptions for Saudi Arabia, Egypt and Pakistan range from 51 per cent to 55 per cent.

Impact on voice traffic:

• India: 82% out of service
• Saudi Arabia: 55% out of service
• Djibouti: 71% out of service
• Egypt: 52% out of service
• United Arab Emirates: 68% out of service
• Lebanon: 16% out of service
• Malaysia: 42% out of service
• Maldives: 100% out of service
• Pakistan: 51% out of service
• Qatar: 73% out of service
• Syria: 36% out of service
• Taiwan: 39% out of service
• Yemen: 38% out of service
• Zambia: 62% out of service

Most of the traffic between Europe and Asia is re-routed through the US. Traffic from Europe to Algeria and Tunisia is not affected, but traffic from Europe to the Near East and Asia (incuding India -- see table) is interrupted to a greater or lesser extent.

The (SEA-ME-WE) SMW-3 and SMW-4 are owned by groups of phone companies including Bharti Airtel [Get Quote] while FLAG cable systems is owned by Reliance [Get Quote] Globalcom (an Anil Ambani owned company). And it was only this February, that damage to the trans-Atlantic submarine (undersea) cables slowed down Internet traffic and affected IT-BPO firms for almost three weeks across India before they were reparied, even as Indian telecom operators were diverting traffic over alternate routes.

Call centres of IT-BPO firms were the most affected then, since the IPLCs were down too. Unsubstantiated sabotage theories were doing the rounds too.

Submarine cables are laid beneath the sea to carry telephone and Internet traffic. They can be broken or damaged by fishing trawlers, anchoring, undersea avalanches and even shark bites. In 2006, an earthquake centred near Taiwan had severed several undersea cables, and Internet services slowed to a crawl across major parts of Asia.

In February, a storm struck the Egyptian coast on January 30, making it impossible for ships to dock at the Alexandria port. This prompted some of the ships to anchor off seas, and it is believed a ship dropped its anchor right on the top of the submarine cable channel.

How are undersea cables repaired?

• Find the location of the accident; drag the damaged part to the surface, and replace it with a new stretch of cable.
• May also send light pulses along the fibres in the cable to determine the exact location.
• A working fibre will transmit those pulses all the way across the ocean; a broken one will bounce it back.
• The telecom operator then sends out a large cable ship with a few miles of fresh fibre-optic lines.
• If the faulty part of the cable is less than about 4,000 feet down, a submersible robot can be sent.
• The robot finds the right place; grabs hold of the cable; cuts out the malfunctioning section, and pulls the loose ends back up to the ship.
• Robots do not work in very deep water. In such cases, technicians use a grapnel to cut the cable and hold it.
• A skilled technician (jointer) splices the glass fibres; uses adhesives to attach the new section of cable.
• The repaired cable is then lowered back to the seabed on ropes.