The BlackBerry Pearl 8120 from Research In Motion (RIM) fits all of the essential BlackBerry features into a device no bigger than a standard phone, and adds Wi-Fi into the bargain. However, its size means that its keyboard is a bit of a compromise, making it less suitable for heavy email use than other BlackBerry models.

Available now through O2, the BlackBerry 8120 is the successor to last year’s 8100 Pearl model, adding Wi-Fi capability but keeping the weight down to just 91g. This makes the device one of the lightest smartphones available, and no heavier than many talk-and-text handsets. However, the new Pearl has the advantage that it can also link to a BlackBerry Enterprise Server to get push email and bring it under central control by a company’s IT department.

Although its small size makes the 8120 easy to slip into your pocket, the slimline design only leaves enough space for Blackberry’s SureType keyboard. This enables the user to key in text, but in many cases is slower and less satisfactory than a full qwerty keyboard. Its screen is also smaller than other BlackBerry models, and some users may find it more difficult to read text for this reason.

The major new feature of the 8120 is its 802.11b/g Wi-Fi support, which we found easy to set up and use. A Wi-Fi setup tool has been added to the applications list, and this allows the user to scan for available networks or manually add a connection. The BlackBerry could not find our test access point by scanning (the access point was configured not to broadcast its identity) but connected after we added its details manually.

By default, the 8120 will automatically re-connect to Wi-Fi networks in the connection list if they are available, and will also automatically use the faster network for both web browsing and email. The BlackBerry supports WEP, WPA and WPA2 security.

Wi-Fi support in the new BlackBerry holds out the possibility of using the device for IP telephony. However, the device does not ship with either a SIP or UMA client to support this, leaving it up to business customers or their systems integrator to provision this feature if needed.

Because the 8120 does not support 3G networks, users will mostly have to fall back on GPRS for email and browsing if there is no nearby Wi-Fi access point. However, we found we were able to get an Edge connection when using our handset on O2’s network in central London. Edge is an enhancement to GPRS that offers higher data transfer rates but is not currently available in all areas of the UK.

Also added is a revamped user interface with a new font rendering technology, although most users will be hard pushed to notice any difference. The icons and display seemed little different to most other BlackBerry devices we have seen since the 8700g handset was introduced in early 2006. That said, we found the display of the new 8120 to be exceptionally bright and clear compared with many rival mobile devices, even if it is a little on the small side at just over 2in measured diagonally.

A further enhancement is a new “Page View” option in the BlackBerry browser that attempts to display a full web page and lets the user pan and zoom using the pearl trackball. However, unlike the browser in the iPhone, we found that this still does not display the web page as you would see it on a desktop PC browser. In many cases, web sites also detect that you are using a BlackBerry and automatically serve up a mobile/PDA version of the site instead of the full version.

For test purposes we were provided with an email account on a BlackBerry server and can verify that emails addressed to the device arrived within seconds of being sent from a desktop PC.

We had a mixed experience using the SureType keyboard to compose emails and SMS text messages. Because each key has two characters on it, the device has to rely on prediction to work out which word you are trying to type. This works pretty well in the body of emails, where you are generally typing plain English, but keying in less familiar words, such as email addresses, can become a frustratingly slow process.

This may be less of a problem for workers if they typically send messages to colleagues by selecting their details from the corporate address book. When making voice calls, the central three columns of keys serve as the numeric keypad.

The pearl miniature trackball, after which the device is named, enables the use of an on-screen pointer in applications such as the browser, where older BlackBerry models had a thumbwheel that could only scroll up and down.

The 8120 also has some more consumer-oriented features, such as its digital camera, now upgraded to 2 megapixels from the 1.3 megapixels of the original Pearl, and capable of capturing video. There is also a media player for music and video content.

The 8120 also features RIM’s BlackBerry Maps application, which can be used for navigation when combined with an external GPS receiver, plus BlackBerry Messenger for instant messaging.

Because the 8120 has the same 900 mAh removable battery as the original Pearl, its quoted battery life is about the same ­ 4 hours talk time and about 15 days on standby. This will obviously be shortened by heavy use of the Wi-Fi interface, however.

Like its predecessor, the 8120 has a slot for MicroSD Flash memory cards, but this is now located in the side of the case and protected by small plastic flap, instead of inside the battery compartment. O2 ships the device with a 1GB card included.

The device also has a mini USB slot for its supplied PC sync cable and its mains charger. A wired headset is also supplied, or the user can use the 8120’s Bluetooth interface to connect a wireless headset.