When Research In Motion announced in March that it was adding phone capabilities to its popular BlackBerry platform, we were intrigued. We are big fans of the company's push e-mail system for corporations, and the RIM BlackBerry 5810 ($500 street plus $20 activation fee and monthly service fee) promised to combine into one handy device a lot of the features mobile business pros need—a personal organizer, corporate and personal e-mail access, GSM/GPRS wireless phone service, short-message sending and receiving (SMS) capability, WAP browsing, and support for custom enterprise apps—into one handy device.

We recently got our hands on one of the first production-level evaluation units. The core BlackBerry functions make this a compelling communicator, but the phone component—arguably the most important addition—is less convenient than it could be.

The drawback: There is no built-in microphone or speaker. To make or receive a call you need to plug in the included headset. If you don't keep it plugged in, you have to have it handy or you'll miss phone calls. In this regard, the 5810 is a less successful, albeit smaller, all-in-one design than, say, the Handspring Treo line. One advantage to RIM's design, though, is that you can see and use its PDA features while on the phone. Still, frequent phone users hoping to pare down to one device will probably find the separate headset bothersome.

One convenient feature of the 5810 is that you can quickly dial phone numbers in the Address Book, in an e-mail, or in SMS messages by scrolling over them pushing the jog-dial activation key. We made and received calls in both GSM and GPRS networks (the current network is displayed on the status screen) And voice quality on both ends of the calls was the same as with typical digital phones.

Two-way SMS is a near-instantaneous method of communicating between wireless devices. It's more popular in Europe, but gaining currency in the U.S. as an effective corporate communications. Using the 5810, SMS text messages go from one device, through the BlackBerry service directly to the intended recipient – much more direct than storing messages in a corporate server.

The 5810 uses the Java 2 Micro Edition (J2ME) operating system, and its enterprise e-mail system is unchanged from prior RIM BlackBerry Enterprise messenger models. This platform's key feature is the always-on push e-mail that works through desktop PC redirection or via the BlackBerry Enterprise Server that integrates with Microsoft Exchange and Lotus Domino servers.

The key differences from previous BlackBerries are voice service, SMS, and the BlackBerry Web Client, which supports POP3 e-mail integration. Being able to receive personal and corporate e-mail on the same mobile device is especially useful. Like its predecessors, the BlackBerry 857 and 957, the 4.8-ounce, 4.6- by 3.1- by 0.7-inch (HWD) 5810 has a highly visible backlit monochrome display, a jog dial for easy screen navigation, a back button, and a small, integrated backlit keyboard.

Records of voice call records, SMS messages, and e-mail all appear on the 5810's single Messages screen, a level of integration that facilitates managing incoming and outgoing messages. For example, if you receive an SMS message that also contains a phone number and e-mail addresses, you can easily reply using any of the three methods.

The BlackBerry Web Client, accessible via any browser, is used to configure e-mail settings such as filters and auto-signatures. You can also configure up to six POP3 e-mail accounts to forward e-mail to the RIM device.

If your business day involves frequent phone conversations, the BlackBerry 5810 may not be for you. But avid BlackBerry users and organizations with existing BlackBerry Enterprise Server users may choose the 5810 as a convenient, highly integrated communication device that handles multiple types of data plus the occasional voice call.