Consumers in Southeast Asia's emerging markets spent a combined $10.8 billion on 41.5 million smartphones during the first three quarters of 2013, GfK estimates.
The combined volume of sales from Singapore, Malaysia, Thailand, Indonesia, Vietnam, Cambodia and the Philippines increased 61% over the nine month period.
GfK said by September the region reached a significant milestone – one in every two handsets shipped is now a smartphone.
Indonesia is the largest smartphone market in the region, with consumers buying 14.8 million smartphones worth $3.3 billion since the beginning of the year.
Thailand was second ranked in terms of sales volume with 7.2 million units, followed by Malaysia at 7.4 million. But in terms of sales revenue, Malaysia is ahead at $2.25 billion compared to Thailand's $1.96 billion.
Thailand along with Vietnam are also the fastest growing markets for smartphones in the region. In Vietnam, sales volumes increased 156%, compared to 118% for Thailand.
GfK's statistics for the period also suggest the SEA region is following the global trend towards devices with larger screens. Sales of smartphones with screens of 4-inches or above more than doubled during 9M13 from 13% to 27%, and phablets are growing in popularity in the region.