Since 2008, the Washington-Moscow Direct Communications Link (also known as "The Washington-Moscow Hotline") uses redundant circuits of two satellite links and a fiber-optic cable. They use commercial facilities for at least part of the circuits.
Past accidents have interrupted previous hotline circuits. A Danish bulldozer operator once cut the line near Copenhagen. A Finnish farmer once plowed it up. A fire in a Baltimore Maryland manhole took it out of service temporarily. Yep, even the hotline experienced cable cuts.