India’s 4G upstart Reliance Jio reportedly is figuring out tariff plans to apply after its expanded free data offers end on 31 March, with the newcomer expected to start 4G data plans with free voice at INR100 (about $1.50) per month.

In a sign the operator understands “free” isn’t a long-term business model, it is working out low-cost data tariffs which will be valid for three months, sources told The Economic Times (ET).

Jio added 600,000 customers per day in its first three months of operation and now says it signed up 72 million subscribers. Capacity issues due to its generous free data offers mean customers are limited to 1GB high-speed 4G before having their data rate reduced.

The ET reckons Jio is not the primary phone connection for many of its subscribers as many have multiple SIMs, and it could lose many of them if it increases rates significantly.

To boost its 4G network capacity to keep up with soaring demand, Jio announced earlier in the week it aims to raise $4.4 billion from existing investors through a rights offer.

The country’s three largest operators have all introduced expanded data offers after Jio extended its free offer from the end of 2016 to end-March as a part of a special new year deal.

Vodafone India was the latest to offer subscribers an additional free increase in 4G data allowances in an attempt to defend its customer base from increasingly strong competition. It is reportedly set to offer four-times the data allowance currently provided on some of its 4G plans.

Both market leader Bharti Airtel and Idea Cellular, India’s third largest mobile operator, introduced their own special offers giving 4G customers additional free data each month.

The Telecom Regulatory Authority of India (TRAI), under pressure from the top three operators, asked India’s Attorney General for his view on Jio’s promotional offers extending beyond 90 days. Meanwhile, Idea filed a case in a tribunal against TRAI for not acting against Jio for what it claims is “predatory pricing” and violating regulations on its free offers.