The Hindu Business Line : Why does the wire go haywire during a jam?

Common causes
Networks get jammed in times of severe crisis like in Mumbai, where operators recorded a 300 per cent increase in the traffic.
The telecom network consists of boxes, exchanges, base stations that are essentially electrical in nature, which may stop functioning due to water logging.
It happens in the case of natural calamities like storms, which can disrupt the radio signals in the case of cellular communication.

New Delhi , July 14

The collapse of the telecom network during the recent bomb blasts in Mumbai and during floods in various parts of the country makes one wonder what makes our communications services so vulnerable.

According to technology experts, there are at least four different situations when the operators, the Government or technology cannot do much to keep you connected.

The biggest and most common cause is when the telecom network gets congested in a crisis situation, just like it happened in Mumbai after the serial bomb blast.

While most telecom networks have the capacity to function even if there is a 200 per cent increase from the normal day peak hour traffic, in times of severe crisis like in Mumbai, operators recorded a 300 per cent increase in the traffic. "In such a situation when the load is higher than the capacity of the network the system collapses just like it would in the case of electricity generating units. However, some of the operators have designed their network in such a way that the system does not collapse but the excess traffic gets rejected, which gives a busy tone in case a subscriber calls into the network," said a leading telecom technology vendor. The phenomenon is not common to India only.

London, NY cases

Telecom networks in London and New York were jammed after the bomb blasts in the sub-way train last year and the twin tower tragedy. Operators say that a similar surge in traffic is witnessed during New Year's Eve or festive season but since these are expected events, they get enough time to upgrade their networks.

"Events like bomb blasts or other natural calamities are unpredictable and it is too expensive a proposition for us to keep excess capacity in anticipation of such a crisis. However, we do deploy technology that can increase the capacity of voice calls up to 200 per cent and three times more short messages," said an Airtel spokesperson.

How to get over it?

Operators also said that a way to get around the problem would be to keep the calls short and communicate more using SMS in times of crisis.

"Short messaging takes less capacity than voice calls because in the latter we have to provide a channel dedicated to the call whereas in messaging, the text can be sent by the network as and when capacity is available," said a Mumbai-based operator.

Another big reason for the networks to stop functioning is floods or water logging. The telecom network consists of boxes, exchanges, base stations that are essentially electrical in nature, which may stop functioning due to the water.

Networks could also get jammed in the case of natural calamities like storms, which can disrupt the radio signals in the case of cellular communication.

"When you talk on a mobile phone, the voice signals travels from one tower to the other for which a line of sight is required between the towers. In case of a storm, the high wind speed can disrupt the sequence," said a technology expert.

Networks can also black out if there is no interoperability between two operators or lack of proper interconnection.

This is more likely for long distance calls where a local operator has to ride on the national long distance operator's network.

Experts pointed out that operators across the globe are looking at bettering the design and architecture of their network to create redundancy, which can weather a crisis situation.

For instance, during the floods in Mumbai, in 2005, when most cellular operators networks had collapsed, almost 300 of Airtel's base stations were down, but engineers from Nokia kept the operator's network alive by providing alternate routing.

While flooding had caused power failure through 60 per cent of the city, Airtel had reconfigured its base stations to optimise power consumption.

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