Reliance Jio's entry has transformed the telecom industry in India in ways one couldn't have imagined. Affordable high-speed mobile internet, low-cost voice calls, free national roaming, and record data consumption are the new norms of any prepaid or postpaid connection. But Reliance Jio has gained an edge over rivals in less than a year.

Unlimited free voice calls over VoLTE network and free 4G data helped Jio flourish in the industry, and gain more than 130 million subscribers in less than a year.

Incumbents were hit bad with Jio's bold stunts, and called out for help from telecom regulatory bodies in India. But the best way to survive the changing trend was to adapt and go with the flow.

Reliance JioFacebook/Jio

Airtel, which is Jio's biggest competitor and also the country's largest telco, put a firm foot forward against Jio's acts by lowering prices of its 4G data packs and giving special deals to match the new telco.

Continuing its stance against Reliance Jio, Airtel is taking the final step that will put both telcos on similar footing.

According to reports, Airtel is going to launch VoLTE services in India as early as next week. This has been a long-overdue update to the largest network in India, which like other telcos used age-old circuit-switch technology for calls.

The Circuit Switched Fall Back (CSFB) technology used by incumbents for voice calls transfers users to the GSM platform to make and receive calls.

India 4G availabilty
An employee of Bharti Airtel Limited runs after adjusting the screens of a promotional billboard during the launch of Airtel's 4G services in Kolkata on April 10, 2012.DIBYANGSHU SARKAR/AFP/Getty Images

Reliance Jio is the only service provider to offer VoLTE service in India as of now, and Airtel will become the first of the established telcos to follow suit.

The Economic Times reported that Airtel's VoLTE services will go live first in Mumbai, followed by Kolkata and other metropolitan cities.

The company has already conducted trials for its new calling network over the past few months, and hopes to expand the VoLTE network across India within this fiscal year (March 2018), people familiar with the matter said.

In this image, Gopal Vittal, Bharti Airtel's chief executive for India and South Asia, is speaking during a news conference in New Delhi, India, November 30, 2015.REUTERS/Anindito Mukherjee

VoLTE calls mean good news for customers. The latest network offers clearer voice as compared to 2G and 3G networks.

By moving to VoLTE, carriers free up 3G and 2G networks, and they can be reframed for 4G data services.

As a result, end-users in India will benefit extensively from better connectivity, speed and range.

The sources haven't mentioned if Airtel's VoLTE network upgrade means free calls for users. But considering the intense competition between Jio and Airtel, the latter would try to level with Reliance Jio and the only way to do so is by offering free calls over VoLTE.

JioPhone launch at RIL AGM
Reliance Jio launches free 4G feature phone aka 'JioPhone' with unlimited voice, dataRIL AGM via YouTube

All of Jio's tariffs currently come with free voice calls, and Jio has no intention to change that. If that's the path Airtel wants to go down, it should at least match Jio's offering. Airtel hasn't commented on the matter yet.

Airtel's VoLTE plans aren't entirely new. Apple India's support page had recently mentioned Airtel VoLTE support for iPhone 6 and above models. Prior to that, Airtel had been testing the necessary infrastructure for its VoLTE service in India and had partnered with various smartphone manufacturers, including Motorola, Xiaomi, Samsung and OPPO, to test the service.

Now the competition is getting more intense due to Jio's recent launch of the first-ever 4G VoLTE-compatible feature phone. Over 6 million people have already pre-booked the essentially-free JioPhone.

With affordable tariffs and now hardware, Jio is moving quickly to dominate the India telecom market.