G.fast—the latest and fastest version of DSL—may eventually deliver a super-fast upgrade in speed to DSL users. Late last year, the International Telecommunications Union (ITU) approved this new version of the digital-subscriber-line (DSL) standard for Internet access over the plain old telephone service (POTS), also known as the public switched telephone network (PSTN). POTS uses the massive installed base of unshielded twisted-pair wiring from telephone central office to the home or office.