RIM and its range of BlackBerry handsets has regained the upper ground against the iPhone, according to new figures out in the US.

According to the NPD Group, a "leading provider of reliable and comprehensive consumer and retail information for a wide range of industries", the research company is claiming that RIM’s 2-year-old BlackBerry Curve (83xx) is the best selling consumer smartphone in America in the first quarter of 2009.

RIM’s consumer smartphone market share increased 15 percent to nearly 50 percent of the smartphone market in Q1 2009 versus the prior quarter, as Apple’s and Palm’s share both declined 10 percent each.

Apple managed to come in second ahead of two other BlackBerry models - the BlackBerry Storm and the BlackBerry Pearl - suggesting the fight for the number one smartphone spot is still well and truly on.

T-Mobile's Android powered G1 rolled in at number 5.

“Verizon Wireless’s aggressive marketing of the BlackBerry Storm and its buy-one-get-one BlackBerry promotion to its large customer base contributed to RIM capturing three of the top five positions”, said Ross Rubin, director of industry analysis at The NPD Group.

The NPD Group said that it compiled and analysed mobile device sales data based on more than 150,000 completed online consumer research surveys each month, and do not include corporate/enterprise mobile phone sales giving the numbers - in the consumer space a lot more validity.

The news comes as AT&T announced on Monday that the newer BlackBerry Curve 8900, first launched in the UK in December 2008, would be making a summer debut in the US.