Reliance Jio Infocomm, the telecom arm of Indian billionaire Mukesh Ambani’s Reliance Industries, reported its slowest profit and revenue growth in six quarters on Friday, hit by higher expenses and a lack of recent tariff hikes.

Jio, India‘s biggest telecom carrier by subscribers, said on Friday net profit climbed to 48.63 billion rupees ($593.2 million) in April-June from 43.35 billion rupees a year earlier, according to a Reuters report.

Its revenue from operations rose 9.9 percent to Rs. 240.42 billion, while total expenses eased 9 percent.

Jio has been investing heavily in network infrastructure to grab a bigger market share.

Earlier this month, it launched a cheap 4G feature phone to tap the country’s vast remote markets, which are still on slower mobile networks.

The launch of the phone is seen as a way to avoid any hit to its overall subscriber base from a likely tariff hike in September, according to Ambit Capital.