BT has been testing the system since 1994 at sites in West London. But it has angered media groups and Internet service providers by the long delay in offering the service. Other network operators, who lease lines from BT, have been unable to offer ADSL until BT clarifies the charges for access to its network. BT is believed to have delayed the launch because of fears that ADSL will take business away from its existing, highly profitable ISDN lines, which are being marketed for Internet use as Home Highway.