According to The NPD Group market research, an aggressive "buy-one-get-one" promotion by Verizon Wireless helped RIM's BlackBerry Curve move past Apple's iPhone to become the best-selling consumer smartphone in the U.S. in the first quarter (Q1) 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, according to NDP.

Based on U.S. consumer sales of smartphone handsets in NPD's report, the first-quarter 2009 ranking of the top-five best-selling smartphones is as follows:

RIM BlackBerry Curve (all 83XX models)
Apple iPhone 3G (all models)
RIM BlackBerry Storm
RIM BlackBerry Pearl (all models, except flip)
T-Mobile G1

"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 more familiar, and less expensive, Curve benefited from these giveaways and was able to leapfrog the iPhone, due to its broader availability on the four major U.S. national carriers."

Smartphones, which represented just 17 percent of handset sales volume in Q1 2008, now make up 23 percent of sales. "Even in this challenging economy, consumers are migrating toward Web-capable handsets and their supporting data plans to access more information and entertainment on the go." Rubin said.

Research In Motion is planning another version of its touchscreen BlackBerry Storm smartphone as part of a continuing push into the retail market, its co-CEO said on Monday.