Sales of personal digital assistants (PDAs) fell in the first quarter, but voice-enabled handset shipments rose 16.6 percent as compared to last year, according to research released by IDC. Worldwide, vendors shipped 107.6 million units in the first quarter.

Voice is the "killer application" for handset devices right now, as both consumers and professionals want to be able to talk to associates and customers while also storing key data on a small device, said Alex Slawsby, an analyst with IDC. This is driving the growth of mobile phones, while sales of PDAs without voice features dropped in the first quarter, he said.

Nokia Corp.'s handsets still lead the world based on shipments, with 38.2 million units shipped in the first quarter, an increase of 16 percent over shipments of 32.9 million units in last year's first quarter. Motorola Inc. was second with 16.7 million units, while Samsung Electronics Co. Ltd. trailed with 13.2 million units. Motorola and Samsung increased their shipments by 17 percent and 38 percent, respectively, over last year's first quarter.

Nokia's strength in branding, worldwide channel distribution and carrier relationships keeps it on top, Slawsby said. The Espoo, Finland, company saw strong sales of its 3510i phone with a color display, and its 7650 camera phone, he said.

While voice handsets have been gaining momentum for several years, converged devices are only now starting to take off. A converged device can be either voice or data-centric, while handsets are centered around voice capabilities, according to IDC. Converged devices, such as smart phones, can also synchronize calendar information, address books or e-mail with a server or PC, IDC said.

Nokia dominated the converged device market, with 980,000 units shipped in the first quarter, good for 57 percent of the market. The entire market grew 438 percent from last year's first quarter to a total of 1.71 million units in this year's first quarter.