A BlackBerry handheld device with both mobile phone and Wi-Fi wireless capabilities is on its way, according to Jim Balsillie, co-CEO of BlackBerry maker RIM (Research In Motion).

Speaking at the JP Morgan Technology Conference on Wednesday, Balsillie said such a converged BlackBerry should come out "in the back half of this year".

RIM is behind its competitors in developing devices with both mobile phone and Wi-Fi functions.

Motorola and Nokia were both selling phones with Wi-Fi and mobile aimed at business users last year. RIM had recently hinted at forthcoming converged phones but until now, hadn't said when they would ship.

"Wi-Fi was overhyped," Balsillie said. "I was not a big believer in it for the first two or three years because it was hyped as something that would subsume everything, that you would get rid of your mobile phone. We feel it's complementary to a mobile phone."

The BES (BlackBerry Enterprise Server) that companies use to deliver corporate email to BlackBerry users already supports roaming for customers that travel between multiple operators, so the BES would treat Wi-Fi networks just like additional mobile phone networks, Balsillie said. That capability enables the handoff of data connections and voice calls between Wi-Fi and mobile networks as customers move.

In addition, the BES "presupposes the airlink is insecure", and so encrypts all voice and data transmissions using either technology, he said. The BES already supports Wi-Fi connections because the BlackBerry 7270 has Wi-Fi.

Many mobile operators, particularly those that aren't related to a landline service provider, have resisted FMC (fixed mobile convergence) because they can lose revenue by transferring calls from their mobile networks to a potential opponent's Wi-Fi network. But Balsillie said the operators are open to it. "Most of the carriers I've dealt with are supportive of FMC," he said.

Also, he's finding that an increasing number of operators have both mobile and fixed-line networks, and those companies are looking for strategic ways to leverage both assets. Services such as FMC can allow those operators to offer a value-added service rather than simply offering a single bill.