HP has unveiled two iPaq models aimed at mobile business users, one focused on messaging and the other on voice capabilities, both featuring a distinctive new navigation control.

The iPaq Voice Messenger and iPaq Data Messenger are both based on Windows Mobile 6.1 and support HSDPA mobile broadband, built-in GPS, Wi-Fi and Bluetooth.

The two models will be available either SIM-free through HP resellers, or with a wireless contract through Vodafone.

HP said that the iPaq Voice Messenger is aimed at users that want a phone for voice calls first, but who may also need to receive emails while on the go.

This handset follows the traditional candybar phone design, but its keypad has two alphabetic characters per key, like RIM's SureType keyboard on the BlackBerry Pearl, and uses predictive text to determine which word a user is entering. It is based on the Standard edition of Windows Mobile 6.1 and weighs about 107g.

The iPaq Data Messenger, meanwhile, is aimed at more data-centric users as its name suggests. It has a slide-out full Qwerty keyboard and a touch-sensitive display designed for stylus input. It is heavier at 160g.

The Data Messenger has a larger 2.8in display and, because it runs the Professional edition of Windows Mobile 6.1, users can create and edit documents using the built-in mobile versions of Word, Excel and PowerPoint. It also ships with Opera's browser in place of Internet Explorer.

Both handsets feature a new optical sensor that replaces the five-way navigator key common to many phone designs. This makes it easier for users to move through menus with greater speed while minimising the chances of mechanical failure, according to Neil Dagger, HP's iPaq and wireless business manager.

"You just glide your thumb over the disk, and you glide though the menus, tapping it when you want to select something," he said.

The HP-branded iPaq models come with a 30-day trial of the Webraska navigation software, which downloads map data and traffic alerts on demand.

HP includes a number of value-add utilities, according to Dagger, such as a configuration tool that supplies the correct country settings automatically, a GPS connection tool for Assisted GPS and a keyboard lock.

Both models also have a power saving mode that minimises power consumption if the battery charge level starts to get low while the user is out on the road.

The iPaq Voice Messenger costs £333 (SIM-free) and is due to ship in mid-November, while the iPaq Data Messenger costs £399 (SIM-free) and will be available from the end of November.

Vodafone pricing has yet to be disclosed, but the operator is likely to offer the devices free depending on the monthly tariff chosen.