As of December 2013, the penetration rate in Sri Lanka was estimated at 99.2% over a population estimate of over around 20.3 million.
The country's telecom regulator is the Telecommunications Regulatory Commission of Sri Lanka (TRCSL).Source.
Around 45-50% of people in Sri Lanka own a mobile phone now. Although this is higher
in comparison to South Asia (30%) and the developing world (40%), mobile ownership in
Sri Lanka is well below that in mature markets which typically see rates of 60-80%.