More than two in five smartphones sold during October were Apple's iPhone 4S, says Kantar Worldpanel ComTech.

According to data released by the research firm, the iPhone 4S accounted for 42.8 percent of all smartphone sales last month, while handsets running Google's Android operating system were the second most popular, accounting for 35 percent of all sales. Furthermore, three quarters of all the iPhone sales in this period were to customers who already own a previous generation of the handset, although just 14 percent were upgrading from the iPhone 4 to the iPhone 4S.

Smartphones accounted for nearly 70 percent of all mobile phone sales during the three months from the start of August this year, and in October alone the smartphone sales market grew 43 percent. However, the whole mobile phone market decreased by four percent in the same period as sales of feature phones decreased by nearly half.

For the three months from August to the end of October, Android remained the most popular smartphone platform accounting for 46 percent of all smartphone sales, which is up on 34.2 percent for the same period in 2010. Apple's iPhone was second with 27.8 percent, also up on last year's 25 percent.

RIM was third and accounted for 19.6 percent of all handsets, which is slightly down on 20.9 percent from last year. Symbian also suffered a loss dropping from 14.1 percent to 3.9 percent.

"The October launch of the hugely anticipated iPhone 4S has catapulted Apple into second place among operating systems based on the last 12 weeks of sales. However, if you just look at the month of October, Apple took a whopping share of all smartphone sales, giving it a significant lead over Android – a feat many thought was impossible," said Dominic Sunnebo, global insight director at Kantar Worldpanel ComTech.

"While unwavering loyalty is clearly great news for Apple, it is likely to be a relief for other smartphone operators. With Apple predominantly driving sales from within its existing customer base, it leaves the field wide open for the likes of Nokia, BlackBerry, Samsung and HTC to focus on converting the remaining 29 million adults who don't yet have a smartphone to their brand."