* Customers up nearly 10 pct
* Revenue up 12 pct boosted by data
* Shares down 8 pct (Adds details)
JOHANNESBURG, March 5 (Reuters) - MTN Group, Africa's largest telecoms provider, posted a 27 percent jump in full-year earnings on Wednesday, lifted by foreign exchange gains and strong growth in data revenue.
Johannesburg-based MTN, which has operations in nearly two dozen countries across Africa and the Middle East, said diluted headline earnings rose to 1,378 cents per share in the year to end-December, from 1,082 cents a year earlier.
Headline EPS, the main profit measure in South Africa, excludes certain one-time items.
MTN said last month its earnings would rise by 25 to 30 percent, citing foreign exchange gains of 1.1 billion rand ($101.96 million). The rand currency lost around 20 percent last year, hit by a sell-off in emerging market assets, and lifting overseas earnings for exporters and internationally focused companies such as MTN.
Revenue rose 12 percent, underpinned by data revenue, which climbed more than 40 percent to 20.7 billion rand. Mobile phone operators are reinventing themselves to rely less on telephone calls and pushing customers to use more data.
Growth in outgoing voice revenue was slower, at 12 percent.
Customers rose to 207.8 million, up nearly 10 percent.
MTN is challenging a South African regulatory decision to reduce the rates it charges competitors to carry calls on its network, arguing smaller operators stand to gain from the decision despite spending much less on upgrading their own networks.
It spent more than 30 billion rand on capital expenditure, up nearly 5 percent.
The company's shares are down more than 8 percent so far this year, compared with 3.8 percent rise by the Top-40 index . ($1 = 10.7890 South African rand) (Reporting by Helen Nyambura-Mwaura; editing by David Dolan)