(Telecompaper) MTN Group said its revenue increased by 6.8 percent on an organic basis to ZAR 132.8 billion in 2017. Underlying service revenue rose by 7.2 percent to ZAR 124.41 billion, thanks to a recovery in Nigeria. Outgoing voice revenue remained largely flat, which it said was a positive re-enforcement of its work to stem the decline in the voice contribution, particularly in Nigeria, where outgoing voice revenue went up by 7.5 percent.