India’s leading mobile operator Bharti Airtel is to increase the prices of voice calls, according to Reuters. And Vodafone may follow the lead of its larger rival, says the report.

Bharti Airtel said it has not increased headline charges but has reduced promotions and free calls offered to subscribers.

However, free calls are being reduced by up to a quarter and the price of some prepaid call vouchers will go up by INR5-15 (10-30 cents), said the report, quoting a source familiar with the matter.

Meanwhile Idea Cellular said the previous day that it lifted voice prices in some parts of the country by dropping promotional offers.

And Vodafone confirmed it might follow its rivals although it not decided on the form of any price increases.

Investors boosted Indian telecoms share on the hope that Bharti’s move would be taken up more widely by other operators.

A similar rise in share prices took place in 2011 when Bharti increased voice prices but the trend was not sustained across the industry.

Certainly, a widespread increase in prices would make sense given the costs associated with the country’s forthcoming spectrum auction.