Orange HD Voice is something we've been hearing about for the last 2 years, first in a demo in 2008, and more recently in confirmation that 2010 was the year.

Orange has now formally announced that the service is planning to roll-out nationwide by the end of summer 2010, bringing improved call quality to customers. First Orange have to test the service though, which is taking place across Bristol, Reading and Southampton. 

HD voice calling depends on a number of factors, the most important of which will be whether you have an HD Voice-enabled handset, which is something that Orange have been working on with leading providers. The trial will be conducted on some Nokia handsets and we tested it with an E72, although not all Nokia E72 handsets in circulation necessarily support the service at this time.

We got to test the HD Voice service this week and in a comparison call against normal (current) calling the difference is not only obvious, but quite exciting. You probably take it for granted that calls on your mobile sound a particular way - it's something that we've all got used to over the past 15 years of mobile phone use.

But we found HD Voice to be clearer, eliminating background noise and making the voice more distinct, but more importantly, it sounded much more natural. Amusingly, we used those words to describe the experience before we'd seen the marketing spiel, or the video above.

There are two components to HD Voice, as it is a service that will come from your handset and the mobile phone network. The system actually works by using a new codec - WideBand-Adaptive Multi Rate (or WB-AMR). This widens the bandwidth of the call from the current 300-3400MHz to 50-7000MHz.

Best of all the HD Voice service will be an improvement to the network you already know, so it will be a value-added feature and won't cost you a penny.

Of course, you'll only benefit from the service if you are on Orange and if you have an HD Voice-capable handset, although Orange previously told us that there would be improvements with just one HD handset. Currently we don't know whether the services will extend beyond the UK, or if it will eventually be a standard across all the UK networks.

We don't currently know which phones currently are HD ready (to coin a phrase) or how they will be updated, or if they'll even need to be. When we find out more, we will let you know.