Global smartphone shipments surged 55 per cent in the fourth quarter, as demand for Apple's iPhone 4S countered declines by Research In Motion and Nokia Oyj, International Data Corporation said.
Shipments advanced to 158 million units from 102 million a year earlier, exceeding IDC's forecast for a gain of 40 per cent.
Smartphone demand is increasing as prices for devices become more affordable, encouraging users to upgrade to handsets on which they can browse the web and send email.
Existing users are also trading up to more powerful smartphones such as the iPhone 4S, which went on sale in October. Apple sold 37 million iPhones last quarter, helping the company to double its profit in the period.
By the end of 2011, one out of every three mobile phones shipped worldwide was a smartphone, and the iPhone 4S "played a key role in smartphone growth to capture pent-up demand", said Ramon Llamas, an analyst at IDC.