The value of transactions processed through mobile point of sale terminals is expected to be A$7.6 billion this year, rising to $21.7 billion in 2016.Mobile payments company Mint Wireless gave an investor presentation last week, and cited mPOS market research from several sources, including Gartner, Timetric, Forrester and MasterCard.Investors were told that, according to Timetric, the number of mPOS terminals in use worldwide rose from 4.5 million in 2011 to 9.5 million the following year. It forecast that 52 million units would be sold in 2018, by which time the installed base of mPOS devices would be larger than the number of traditional point of sale terminals.Forrester said that 78 per cent of retailers were piloting mPOS applications or planning to introduce mPOS.MasterCard found that 75 per cent of the merchants that started using mPOS in 2010 and 2011 had not previously accepted card payments.