Although the concept of a dual-SIM phone isn't new, it's never been promoted widely. The UK's Tattu Mobile hopes to change this. It launched the TS500 at the Mobile World Congress this week, with plans to sell the phone nationally in the next few months. A dual-SIM phone lets customers use two SIM cards and two mobile numbers simultaneously; perhaps for home and work or for combining special offers for calls and texts. The TS500 is a slide-open tri-band device with a 2-megapixel camera, music player and FM radio. [Press release (pdf)]