HD Voice technology isn't particularly new -- in fact, some UK operators have supported it since as far back as 2010. Very few devices were HD-capable back then, though, but lots of modern smartphones are now suitably equipped, leading other carriers to get their acts together. Today, Vodafone announced it's joining the party, letting anyone with a supported handset make HD calls to others on the same network. HD Voice, if you weren't aware, widens the frequency range of your call, ensuring conversations almost sound like you're talking to someone face-to-face. Today's launch means O2 is now the only major UK carrier not offering the feature, and it says it has no official plans to either. Given most smartphone usage is dedicated to messaging and photo apps these days, today's launch might not excite Vodafone customers all that much. The difference in quality is noticeable though, so prepare to feel like someone's living inside your head the first time a call connects in HD.