Many local authorities used legislation designed to protect buildings of architectural or historic importance to keep old telephone boxes in prominent locations and around 2,000 of them were given listed status. Several thousand others were left on low-revenue mostly rural sites but many thousands of recovered K2 and K6 boxes were sold off. Some kiosks have been converted to be used as shower cubicles in private homes. In Kingston upon Thames a number of old K6 boxes have been used to form a work of art resembling a row of fallen dominoes. As of January 2020, it was estimated that 8,000 traditional red telephone boxes remain in public service. The KX+, better known as the KX100 PLUS, introduced in 1996 featured a domed roof reminiscent of the familiar K2 and K6. Subsequent designs have departed significantly from the old style red boxes. BT followed the KX series with the Multi.phone in 1999 and the ST6 in 2007.