Apple's iPhone could become the biggest-selling device in the US within the next six months, analysts at Strategy Analytics report.

The researchers reckon over 1.1 million iPhones were sold in the third quarter, meaning Apple's sold 1.325 million of the devices since the iPhone shipped in the US alone.

"The iPhone has become AT&T's top selling device, commanding some 13 per cent of AT&T's overall handset sales, and the fourth top selling handset in the US market," said Barry Gilbert, vice president of the Strategy Analytics BuyerTRAX programs.

He added: "Although the iPhone hasn't had an expansionary impact in the market, the iPhone has quickly assumed a leading market share position and raised the ante for smart devices. The sales trajectory we are observing with the iPhone could make it the top selling device in the US over the next 1-2 quarters."

Motorola's RAZR V3 is the current top-selling handset, the researchers claim, but its lead appears to be trailing off. It's a game to play for - Strategy Analytics observe that the top ten handsets account for 25 per cent of total handset sales in the US market.

A second recent survey from ChangeWave points out that iPhone's ascendancy has come mainly at the expense of Motorola, which has seen its market share fall over 29 per cent since the iPhone's debut in the US on 29 June.

"The typical iPhone buyer is upwardly mobile, college educated with a six-figure household income," according to David Kerr, vice president of the Strategy Analytics Global Wireless Practice. "While the largest percentage of iPhone buyers is between 20-30 years old, the fact that nearly 25 per cent were between 50-60 years old demonstrates that the device attracts buyers across a broad age spectrum."

At present, iPhone users are quite satisfied with phone design and features, however, they are slightly less enamoured of actual iPhone reliability, battery life, documentation and customer support, the researchers said.