Bharti Airtel, India's leading mobile phone carrier, posted a bigger-than-expected 31.5 percent fall in quarterly profit, hit by losses at its African operations.
Bharti's prospects in its main market in India, the world's second-biggest and fastest-growing by mobile customers, have improved after call prices steadied last year following a vicious price war that led to sharp drops.
Companies including Bharti have recently started rolling out third-generation (3G) networks and are eyeing a pickup in premium data services to boost margins after they spent a total $15 billion at auction last year to buy costly radio spectrum.
But Africa remains a worry for Bharti. It acquired the loss-making mobile operations of Kuwait's Zain in 15 countries last June in a $9 billion deal and became the world's fifth-biggest mobile carrier by subscribers.
Shares in Bharti, valued at about $32 billion, fell as much as 4.7 percent after the earnings to 352.20 rupees in a slightly higher Mumbai market.
Bharti, 32.3-percent owned by Southeast Asia's biggest phone firm SingTel, said consolidated net profit fell to 14 billion rupees ($314 million) for its fiscal fourth quarter ended March, from 20.44 billion reported a year earlier.
It was the fourth consecutive quarter of falling profits for Bharti, since it started reporting results based on international accounting standards.
Net sales rose to 162.65 billion rupees from 107.49 billion.
A Reuters poll of 10 brokerages had on average expected net profit of 16.32 billion rupees on revenue of 163.28 billion rupees for the New Delhi-based firm that now operates in 19 countries across Asia and Africa.
Bharti accounts for a fifth of India's mobile market of more than 800 million customers. It operates second-generation mobile services in all 22 telecoms zones in the country and has rights to offer 3G services in 13 of them.
India's mobile market has been hit by a multi-billion dollar telecoms licensing scandal that has rocked the government and businesses. Bharti has not been implicated in the scandal.