Despite a pick-up in mobile data revenue, Bharti Airtel, India’s largest mobile operator, posted its fifteenth consecutive year-on-year drop in quarterly profit.

Q2 mobile data sales more than doubled to INR15 billion ($245 million) year on year, contributing 7 per cent of overall revenue (INR213.2 billion). Mobile data accounted for 3.9 per cent of overall revenue during Q2 2012.

Moreover, group revenue was up 10 per cent compared with Q2 2012 (INR193.9 billion) with mobile data contributing 39.1 of overall incremental revenues.

However, net income for the three months ended September was INR5.12 billion, a 29 per cent slump from INR7.21 billion in Q2 2012.

The Indian rupee was largely to blame, depreciating 5.2 per cent during Q2 2013 (and closing 19 per cent lower compared with 30 September 2012). It meant forex losses of INR3.42 billion for the quarter.

Analysts, according to Reuters, were expecting a Q2 net profit of INR6.9 billion.

More encouragingly, Airtel seems to be running a tighter ship in the cut-throat Indian market.

Underlying Q2 cash profits – or EBITDA – was up 15 per cent, to INR68.3 billion, year on year. It helped boost the EBITDA margin from 30.6 per cent (Q2 2012) to 31 per cent.

In its home market, Airtel managed to boost its mobile subscriber base by 4 per cent, to 193.4 million, compared with end-September 2012. Over the period, monthly ARPU was up 8 per cent, to INR192.

Comparisons with Q1 2013 are worryingly less impressive. Airtel’s subscriber base grew by a more modest 1 per cent and ARPU was down 4 per cent.

But there seems plenty of scope for data revenue growth given that Airtel, as of 30 September, had only eight million 3G customers signed up to data packages.

Airtel’s business in Africa (comprising operations in 17 countries) make up around a third of group revenue when expressed in US dollars. Q2 revenues on the continent, year-on-year, were up 2 per cent to US$1.12 billion.

Mobile data has been growing steadily across the continent. Data customers now represent 26.4 per cent of Airtel’s total African customer base (66.4 million) compared with 23.8 per cent in Q2 2012.