Research In Motion has launched a BlackBerry that can work on cellular and Wi-Fi networks.

The new 8820, RIM's first dual-mode BlackBerry, will be available from various carriers worldwide over the coming weeks. It features a QWERTY keyboard, a 320 x 240 display and a trackball navigation system.

Pricing was not announced. Previously, AT&T, which is offering the device to US users, has offered some BlackBerrys for as low as $50, plus a monthly voice and data service plan.

The 8820 includes GPS support, a media player and a slot for micro-memory cards up to 32GB, RIM said. The battery is removable, according to the vendor.

The new smart phone switches "seamlessly" between EDGE, GPRS and GSM networks and 802.11a/b/g Wi-Fi, according to RIM. It can operate with the BlackBerry Internet Service, allowing a user to manage up to 10 personal and corporate email accounts, or with BlackBerry Enterprise Server installed inside a user's business.

The phone comes with voice-activated dialling, conference calling, speed dialling and keys for muting calls and other functions. A speaker-phone and Bluetooth 2.0 support are provided.

Wi-Fi security includes Wireless Equivalency Protocol, Wi-Fi Protected Access and WPA2. Also, Cisco Compatible Extensions are included, as well as support for VPN gateways from Cisco, Check Point, and some other virtual private network vendors.

Gartner analyst Ken Dulaney said the 8820 is "great," adding that "when RIM does something, it usually works well." He said it will be interesting to track whether people start using Wi-Fi for voice to bypass cellular carriers.