India notched up its billionth mobile phone subscriber in October, the country's telecoms regulator said, underscoring the importance of its fast-growing mobile market, the world's second largest after China.

Mobile phone subscriptions have boomed in India in recent years as aggressive cost-cutting by its 12 hyper-competitive operators has driven down prices, leading to some of the cheapest tariffs in the world.

The number of mobile subscribers rose by nearly 7 million in October from the previous month to surpass one billion, the Telecom Regulatory Authority of India said Wednesday, hitting a milestone that China reached in 2012.

"It is a matter of great pride for us. It shows an empowered India and an engaged India and a tech-savvy India," Communications and IT minister Ravi Shankar Prasad told the Times of India newspaper.

"It will mean more data, more government-to-government connectivity, more broadband," he said.

The figures do not indicate that India has one billion individual mobile phone users, however, as many people have more than one connection.

"Dual sim" phones are particularly popular, allowing the country's cost-conscious consumers to use two different mobile plans to get the cheapest rates for local or national calls, for example.

In poorer Indian states such as Bihar, "teledensity" -- the penetration of telephone connections for every hundred people -- is as low as 54 percent, with a stark urban-rural divide.

But it still represents remarkable growth in the market since 2000, when there were just two million mobile subscribers in the country, according to research firm Ipsos.

"India is adding 10 to 15 million mobile subscribers every quarter -- that's big," Bhasker Canagaradjou, head of business consulting at Ipsos in Mumbai, told AFP.

"It is the fastest-growing market globally -- even China is not growing as fast," he said.

With more than 200 million Indians mostly in rural areas yet to get their first phone and others rushing to trade up to smartphones, growth is unlikely to slow down dramatically, Canagaradjou said.

For many people in India, a mobile phone represents their sole means of accessing the Internet, with smartphones leapfrogging desktops as the most common way of getting online.

Cheap, mostly Chinese-made smartphone handsets are available from as little as around 1,000 rupees ($15), with many people waiting for free wifi connections to get online instead of buying expensive data plans.

Seeking to capitalise on this, Google recently announced a plan to install free wifi at 400 Indian railway stations across the country over the next three years.