A dual-SIM phone lets you mix work and play by having two SIM cards in one phone, so you can make and receive calls and texts from both numbers. That way, you can take calls from the Justice League while still keeping up your secret identity when you text your nan.
It's also handy if you travel a lot and use two SIM cards to avoid roaming charges. The concept is a rare beast here in the UK, although it's more common in Asia.
And be still our beating hearts, because Onyx promises us the next phone it releases will have Google's Android operating system -- the same OS that's on the HTC Hero. It's proven itself to be powerful, flexible and easy to use, and it'll be the first dual-SIM Android phone we know of.
Until then -- and the date is undecided -- we'll have to be satisfied with the Flip, a flip phone, the Slider, a slider phone, and the Nero, which breaks the does-what-it-says-on-the-tin trend by being a touchscreen phone rather than a Roman emperor.
They aren't the prettiest fillies in the paddock, but they're better-looking than the Acer Tempo DX900, which has been one of your only dual-SIM choices up till now.
Other than sporting two SIM-sized holes, the phones have few features to get our juices flowing.
The Flip has a 1-megapixel camera, a music player and an external screen that shows a clock and incoming calls. The Nero has a 2-megapixel camera, a music and video player, an email client and an FM radio. Judging by the picture, it's also working a user interface with home-screen widgets, similar to the Samsung Tocco Lite. The Slider has a 2-megapixel camera, and a music and video player.
There's no word on prices or availability for these SIMfests, but Onyx tells us it's negotiating now to push them into shops and on to network deals. As well as the Android phone in the works, it's also working on a dual-SIM phone with an 8-megapixel camera, and one running Windows Mobile.