T-Mobile has started selling the much-rumoured Samsung Katalyst Wi-Fi VoIP handset in the US. Available at just £40, the question is when it will reach us here in the UK.

The Samsung SGH-T739 Katalyst allows you to call your friends and family free of charge using VoIP services when you're within range of a Wi-Fi network. When you're not, the phone automatically switches to a mobile GSM network so that you can continue yakking away without interruption.

The slider handset features quad-band GSM/GRPS/Edge connectivity, a 176 x 220 and 262,000-colour screen, 1.3-megapixel camera, expandable microSD card slot up to 2GB and Bluetooth 2.0, Register Hardware reports.

The Samsung SGH-T739 Katalyst is said to offer around five hours of talk time and up to 240 hours of battery life in standby mode. The handset is available on T-Mobile in the US, from around $80 (£40), depending on what contract you're on. T-Mobile could not confirm a UK release date.