Rather than waiting for Apple's iPhone, you might want to consider a rival you can buy sooner. Samsung's innovative, super-slim, two-faced UpStage (M620).

On the eve of the giant CTIA Wireless trade show in Orlando, Florida, Sprint Nextel announced that it will begin selling the UpStage in the US on 1 April. Its price will be $300, or $150 with a two-year contract, Sprint representatives say.

Unveiled in January at CES (the Consumer Electronics Show), the UpStage is a chocolate-bar style handset that's less than half an inch thick and not much taller or wider than an iPod nano.

Other multimedia-friendly mobile phones struggle to balance the sometimes-conflicting requirements of a conventional handset and a music or video player. The UpStage solves this quandary by simply putting phone functions on one side of the device and the multimedia functions on the other.

Face of a phone

The UpStage's phone face has a 1.4in sliver of a colour screen, a directional toggle and a keypad - one with soft, flat keys. The music-player/multimedia side features a 2.1in, 176-by-220-pixel display and a touch-sensitive navigation pad with a central button on the other.

A small Flip button on the edge of the unit toggles between the two sides, but the prompt that confirms you want to stop playing music (on the music side of the phone) and make a phone call gets old pretty quick.

The phone side will of course spring to life for incoming calls, halting music playback; the music resumes once you disengage the call.

The UpStage felt small but solid in my hand; I found its keypad quite usable, and the sound quality on voice calls was generally good. The four-way touchpad on the music side has a central, mechanical play button that took some getting used to. The excellent documentation (including a printed manual of over 300 pages) warns against trying to swipe it in a circle the way you would an iPod's control wheel, but the temptation is hard to resist. It also took a while for me to stop trying to use the central button for directional navigation (instead of tapping the touchpad above, below, or to either side of the button).

Switching sides

Even when the music/multimedia side is activated, you'll have to use the phone side whenever you need to input text - for example, to create a playlist, search the Sprint Store's music catalog or specify a URL for a site you wish to visit in the small-screen-optimised browser.

I was a little confused the first time I encountered a text-input box on the music side, since no alphanumeric keys and no software keyboard appeared. But the device is smart enough to recognise the need to use the phone side, and I noticed that "Flip" had appeared on screen as a soft-key option.

When I used it and began entering text from the phone keypad (T9 text input mode is a welcome option here), "Save/Flip" also appeared as a soft-key option to return me seamlessly to the multimedia side.

Your music or Sprint's

When you first flip to the music side, the UpStage screen (outfitted with rather unattractive wallpaper that looks like a still from one of those iPod animated TV ads) displays three icons. By default, the central icon is highlighted; this musical note icon activates the phone's player functions.

To its left is a small PC icon for invoking the phone's synching mode, and to the right is a dollar sign (appropriate choice) that gets you to the Sprint music store for acquiring tunes over the air.

In synching mode, you can transfer music from a PC to a Micro-SD card that you slide into a slot below the Flip button. (The phone comes with a 64MB starter card, and it can support cards with capacities up to 2GB.) Before synching, however, you must install and run the included Sprint Music Manager desktop application and connect the phone to your PC using the included USB cable. Only then will you be ready to select the "Sync My Music" icon.

The Sprint desktop application is reasonably intuitive to use, although it's no Windows Media Center or iTunes killer. When you launch it, it searches for and builds a library of your MP3, Windows Media, and WAV tunes.

The phone can import files in all of these formats as long as they aren't copy-protected; Sprint says it will convert Windows Media files without DRM to AAC+ format before uploading them to the UpStage.

Once the phone is connected to the PC, you simply drag-and-drop tunes (or albums) from the desktop application's lefthand pane to a lower-right pane. The application will check whether the memory card has enough free space to store the tunes you've selected; if not, it won't start transfers until you've winnowed down your list so the music fits. You can create playlists on the phone itself.

In the connected mode, you can also use the desktop software to play music from the phone, or to transfer tunes you've purchased from the Sprint store to your desktop. But don't expect great quality from these tracks: the music is recorded at a very low bitrate in the expectation that they'll be played primarily on a phone.

As someone who has spent a fair amount of money on high-quality music earphones, I appreciated Sprint's decision to substitute an earphone adaptor (complete with a microphone) for the usual mediocre-quality earbuds. I happily plugged my Etymotics earbuds into the adaptor, and I got great-sounding audio for both music and voice.

A clothes clip on the adaptor solves the problem of the microphone dangling fairly far from your mouth after you plug in your own headphones.

The battery wallet

Another of the UpStage's innovative features: a stylish flip case with an embedded battery (Samsung calls the case a wallet). The case's purpose is both to protect the two-sided phone's screens and to help prolong the phone's useful life between charges.

The phone slides into the wallet and fits into a rigid cradle at the hinge. The included charging cable charges both the phone's battery and the wallet's battery.

When stored in the wallet, the phone recharges itself from the wallet's battery. Sprint and Samsung's fact sheet says the phone's battery will support 2.5 hours of continuous talk time, which rises to 6.3 hours with the help of the battery wallet.

Beyond the music

Of course, the battery gets sapped more quickly if you make heavy use of Sprint Power Vision features such as Sprint TV, which provides access to an assortment of free and for-fee video clips (all incoming phone calls roll over to voicemail while you're using the video service).

The UpStage includes a 1.3Mp camera with tools that let you adjust brightness, optimise photos of handwriting (for digital "postcards"), add a frame to an image, and the like. The camera can also capture MP4 video at 15 fps (frames per second) in clips running up to 30 seconds.

In addition, the UpStage comes with support for subscribing to and listening to mobile podcasts via VoiceIndigo's free mobile service. You can also initiate calls to contacts using Sprint's Voice Command service. And the phone's Bluetooth radio supports headsets and hands-free kits, and you can use it as a PC modem.

Could the UpStage seriously challenge the as-yet unreleased iPhone? That remains to be seen. The UpStage has some drawbacks: Its screen is on the small side for video viewing, and without a qwerty keyboard, it falls short as a serious device for messaging or email.

Then again, the iPhone's innovative software keyboard has yet to prove itself in the field, and the UpStage is a lot more affordable - in the US at least. If video and email or messaging aren't top priorities, music lovers might find the Samsung approach really does UpStage Apple's.