The 3G technology, designed to be fast enough to handle streaming audio and video for mobile phones, is seen as the future focus of earnings growth for mobile companies. The huge costs of putting the services together, however, has alarmed investors and governments.
Investors are also concerned about the time span for rolling out commercial networks.
Vodafone said on Tuesday it expected commercial 3G services will be launched in the second half of 2002, with its services covering 80 percent of the UK population by 2007. Vodafone launched a network two weeks ago to provide customers with faster data transfer on mobiles, and the voice trial is another step towards full 3G services. Vodafone's statement failed to bolster its shares, however, amid a general sell-off on Tuesday of tech and telecom shares across Europe. The mobile operator's stock fell as much as 6.8 percent in London to 201.25 pence. Pages will open in a new browser window External sites are not endorsed by CNN Interactive.