Apple is likely to sell 37.3 million iPhones this year, says a financial analyst.

Brian Marshall of Broadpoint AmTech said that when the counting is done, Apple will have sold 11.3 million phones in the fourth quarter of 2009, a figure that's nearly 30 percent higher than most Wall Street analysts estimate.

Marshall explained his higher-than-average sales estimate by citing the enormous potential Apple has outside the US, where he believes as many as 8.8 million iPhones were sold in the last three months of 2009.

"Based on our analysis, we believe Apple's current global footprint of the iPhone is [approximately] 90 countries, with 140-plus carriers offering the device," Marshall said.

"[That] contributes to a current service available market of 1.73 billion subscribers of which 29 percent, or 511 million are post-paid."

Post-paid refers to the billing method where customers pay a monthly bill after service is rendered, as opposed to pre-paid mobile plans where consumers purchase a set amount of minutes.

If Marshall's numbers are on target, it would mean another record quarter for Apple. The current record of 7.4 million iPhones was set in the quarter that ended September 30, 2009.

At the time, Ezra Gottheil of Technology Business Research, dubbed the quarter - during which Apple also sold a record number of Macs - "spectacular".

In 2010, Apple will do even better, said Marshall, who has put the year's global iPhone sales at more than 37 million, an increase of 35 percent over his estimate of 27.7 million for calendar year 2009.

Again, the upside for Apple is its potential to rapidly grow international sales.

"Despite the enormous success of the iPhone since inception in July 2007, we strongly believe the device is still in its infancy with respect to penetrating the global post-paid subscriber market," Marshall said.

"Our analysis indicates that while the iPhone currently enjoys five percent penetration of AT&T's post-paid subscriber base, the penetration of its current international carrier partners' post-paid subscriber base is only 0.8 percent."

Even so, Marshall wasn't about to belittle the iPhone's impact in the US, and on AT&T's revenues.

Saying that the iPhone's importance to the US wireless market "cannot be overstated", he said his analysis showed that the iPhone is "by far the single most important driver of the post-paid subscriber addition market in the US today".

Marshall's numbers for 2010 aren't out in left field. Gene Munster, senior research analyst with Piper Jaffray, pegged 2010's iPhone number at 36 million, just 4 percent under Marshall's estimate.

According to AppleInsider, which quoted Munster, his estimate for 2009 is 25.7 million, again slightly under Marshall's.

Apple will unveil its fourth quarter earnings later this month when it holds a conference call with reporters and analysts.

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