Combining multiple functions into a single device -- a.k.a. “convergence” -- usually means either trimming back on features or increasing the size of the device to accommodate additional functions. Sony Ericsson’s $499 W800i Walkman phone does something pretty amazing: It merges an MP3 player, digital camera, mobile phone, and even an FM radio into one small, comfortable device, while maintaining a tight integration and full functionality of the components.

As a mobile phone, the W800i performed well. Audio quality on calls was good, both on the handset and the wired headset.

The headset itself is unique in its two piece design. The lower half of the cable connects to the phone and has a microphone and headphone jack built into it. This allows you to replace the included stereo headphones while maintaining phone functionality. The W800i is an international tri-band phone, meaning it only has support for the 900, 1800, and 1900 Mhz GSM frequencies. Unfortunately, it does not support the 850 Mhz band currently being used in many parts of the United States. Anyone considering this phone should check with their carrier to ensure the phone is going to work for you in the areas you need it.

The W800i has a dedicated Walkman button on the top of the keypad that launches the MP3 player, as well as all of the typical playback options available. Moving through tracks is handled with the four-way stick. The Walkman functions are seamlessly rolled into phone. While the MP3 player is running, I was able to use any of the other phone features, like text messaging or the contact list. If you receive a call while listening to your tunes, the W800i will pause the music, ring and announce the call, and return the exact spot after you complete the call. Music can be transferred to it simply by plugging in the included USB cable. The phone sets the included 512 megabyte memory stick up as a USB mass storage device, so transferring MP3s is a simple matter of dragging and dropping. The phone even charged its battery off the USB port while plugged in.

The device is oddly particular in how it wants the MP3s stored, requiring that you create a folder for the artist, then another folder for the album, then store the tracks under that. Transferred music sounded great through the headset and surprisingly good through the built in speakers.

If your own music isn’t enough for you, the W800i also has an FM Radio with Radio Data System (RDS) support. RDS allows read station and song information being sent as text from RDS equipped radio stations. The radio functions also integrated well into the overall phone design.

The built in 2.0 megapixel camera features a great design. The lens cover slides open and launches the camera application. The on-screen viewfinder goes into landscape mode, forcing you to rotate the phone. This puts the shutter button on the top right side, right where you’d expect to find it. The camera can also be toggled into recording video clips easily from the main window.

Overall battery life was good. MP3 and radio functions, however, took their toll on available juice. With average phone and music usage, expect to charge the phone every night.

The W800i is, for the most part, what a convergent device should be. It is able to put a lot of function into a small device, yet not skimp on the quality of any of them. Unfortunately, the lack of the 850 Mhz band support is going to cause problems for this phone in certain parts of the country. But for those that truly want to have it all in one package, the W800i is at least worth a look.

Sony Ericsson W800i Walkman phone, $499 http://www.sonyericsson.com