HTC unveiled the S740 in August, but it has taken a while to reach the UK.
"The HTC S740 combines a powerful, premium phone with a full slide-out keypad in a compact and sleek form factor," said Dr Florian Seiche, HTC's European vice president, at the launch.
"Clearly, one size does not fit all, and the S740 will play an important role in expanding our growing portfolio of devices."
However, even now its release will be limited to just one mobile provider. Orange said that the phone would be sold through its usual channels, and is pitched at business users that are "always on the move".
The handset is powered by Windows Mobile 6.1, and lets users synchronise with Outlook email and calendar information. To further support the use of Windows applications, including Word, Excel and PowerPoint, the S740 features a full slide-out Qwerty keyboard as well as a four-row keyboard for quicker text entry.
Connectivity options include 3G, HSDPA and Wi-Fi, letting users choose how to get online when out of the office.
Orange claims that its high-speed network covers 94 per cent of the UK population.
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