The line that separates a business handset from a mainstream consumer one is hazy at best, and Nokia’s forthcoming E51 is a prime example.

The company’s E-series is aimed squarely at business users, yet there are enough multimedia features to make the E51 appeal to non-business types as well.

Nokia supplied us with a prototype (the handset won’t be available until November) and said it was very close to the finished article, but this prevents us from awarding a final score.

The phone is just 12mm thick and looks similar to the E50, though two new shortcut keys have been placed next to the centre four-way directional pad; the button in the middle of the four-way pad has also been made slightly bigger. It feels great in the hand and usability is equally impressive; buttons are large enough to bash out extended emails and notes.

The 2in display (240x320) won’t appeal to those wanting to watch video, but it’s of a good quality and is fine for browsing web pages.

Connectivity is excellent; GPRS, EDGE, 3G and HSDPA are joined by 802.11g Wifi. Email support is also impressive, with Activesync, Mail for Exchange, Visto Mobile and Seven Always-on are all catered for. And with poor battery life plaguing many new phones, it was good to see the E51 holding its charge for around four days with general usage.

The 2-megapixel camera at the rear lacks an LED flash, but it’s fine for taking quick snapshots. Other features include an FM radio (though you’ll need a 2.5mm adapter to use your 3.5mm headphones), Bluetooth 2.0 and a mini-USB socket.

There’s no built-in GPS and the slim screen might dissuade some, but Nokia’s done an excellent job with the E51 and it looks set to be just a popular with business and home users alike.