Mobile networks now cover more than 90% of the world's population, with subscribers set to reach 5.3 billion by the end of 2010, according to the ITU.
The number of 3G users has grown to 940 million this year, with 143 countries now offering 3G commercial services, the ITU said.
The volume of SMS has tripled over the last three years to hit 6.1 trillion in 2010 – the equivalent of nearly 200,000 sent every second.
Around 3.8 billion of the world's mobile customers will come from developing nations by the end of the year, according to ITU telecom director Sami Al Basheer.
“Mobile phone penetration in developing countries now stands at 68% — higher than any other technology before,” he said.
Asian markets are generating the biggest number of subscriber adds, with China and India expected to sign another 300 million customers this year alone.
Mobile's success in developing regions is down to its affordability, the ITU said – the average monthly subscription costs the equivalent purchasing power of $15, compared to $18 in developing nations.