There were 592 million slotted phones shipped worldwide in 2007, representing 53 per cent of all mobile phone shipments, according to a survey by Strategy Analytics.
It reports that, with nearly 57 per cent of slotted phone shipments in 2007, the microSD (including microSDHC) slot format is now more popular than the MMC format.
The microSD format is expected to hit peak penetration of 86 per cent in 2011, after which it will face competition from other, new, high capacity systems, such as the Universal Flash Storage (UFS).
Steve Entwistle, vice president of the Strategic Technologies within Strategy Analytics, said penetration of slotted phones was already over 85 per cent in many developed countries.