Research firm IDC today released first-quarter 2012 smartphone numbers that show Samsung taking the lion’s share of the market, followed by Apple and Nokia. The shake-up in rankings comes amid a 1.5 percent decline in the mobile phone market year-over-year.

According to IDC, vendors shipped 398.4 million units in the first quarter compared with 404.3 million units in the first quarter of 2011.

And while the overall mobile phone market declined, the global smartphone market grew 42.5 percent year-over-year in the first quarter.

Kevin Restivo, senior research analyst with IDC’s Worldwide Mobile Phone Tracker program, said in a statement that the smartphone segment’s new leader, Samsung, has done a few things right recently. “Samsung has used its established relationships with carriers in a mix of economically diverse markets to gain share organically and at the expense of former high fliers such as Nokia.”

Ramon Llamas, senior research analyst with IDC’s Mobile Phone Technology and Trends program, said that both Samsung and Apple grew in strategic areas. “Apple launched its popular iPhone 4S in additional key markets, most notably in China, and Samsung experienced continued success from its Galaxy Note smartphone/tablet and other Galaxy smartphones,” Llamas said. “With other companies in the midst of major strategic transitions, the contest between Apple and Samsung will bear close observation as hotly-anticipated new models are launched.”

IDC reports Samsung shipped 42.2 million smartphones, followed by Apple (35.1 million) and Nokia (11.9 million).

Nokia’s Symbian phone shipments declined precipitously last quarter as demand dropped in key emerging markets, such as China. IDC stressed that a speedy transition to Microsoft’s Windows Phone operating system is critical.