India’s largest mobile players are fighting back against 4G newcomer Reliance Jio’s generous free offers by launching their own free voice plans or expanding prepaid 4G data allotments.

Market leader Bharti Airtel and number three operator Idea Cellular this week introduced prepaid data plans with free voice, while second ranked Vodafone India offered to double customers’ 4G data allotments, which effectively reduces data prices by 50 per cent, the Economic Times reported.

The operators’ defensive moves are aimed at retaining their prepaid customers as Jio’s free offers attract low-end users. Jio claimed last week to have signed up 52 million customers in less than three months since its launch in early September.

Adding to the incumbents’ woes, Jio is extending its free voice, data and video offer from the end of the year to the end of March as part of a special new year offer.

The upstart’s free offer is expected to reduce mobile operators’ revenue by between 5 per cent and 7 per cent over the next two quarters, according to credit rating agency ICRA. Fitch Ratings last month predicted Indian operators’ blended tariff will decline by 5 per cent to 6 per cent.

Airtel and Idea now offer similarly priced prepaid 4G plans, bundling free voice with 300MB of data for INR145 ($2.14) and INR148 respectively, and 1GB for INR345 and INR348 respectively, according to the Times. Vodafone’s new ‘Double Data’ plan offers 2GB of 4G data for INR255. Number four Reliance Communications’ 4G data plans start at INR149 for 300MB. When Jio starts charging customers in April, it will price 300MB of data along with free voice at INR149 and 2GB at INR299. The plans from all operators generally cover a 28 day period.

Despite Jio’s free offer, the top three players have continued to add subscribers. Airtel added four million users in Q3, Vodafone picked up 2.4 million and Idea added 4.3 million, according to GSMA Intelligence. About 95 per cent of India’s one billion mobile connections are prepaid.