The rest is shared between Mobitel, a unit of Sri Lanka Telecom, Tigo a part of Millicom International Cellular and Hutchison Teleocom. Bharti Airtel Lanka, the locally incorporated subsidiary, is the fifth mobile operator to be licensed in the country.
The firm says it will focus on value added services like financial transactions and music.
Sanjay Kapoor, president of Mobile Services of Bharti Airtel, said the island's offers exciting growth prospects with a mobile phone penetration of 30 percent and two million customers being added each year.
"Our focus will be on affordability and usage and innovation and easy availability," he told a news conference.
"We will invest 200 million dollars over the next five years, with most of it in the first 12-18 months, to set up and expand services."
The company is a unit of Bharti Enterprises, a big Indian telecom service