The lowest grade of unshielded twisted-pair (UTP) cabling. Category 1 cabling was designed to support analog voice communication only. Category 1 cabling was used prior to 1983 for wiring installations of analog telephone systems, otherwise known as the Plain Old Telephone Service (POTS).
The electrical characteristics of category 1 cabling make it unsuitable for networking purposes, and it is never installed as premise wiring. Instead, all premise wiring must use either category 3 cabling, category 4 cabling, or category 5 cabling, with category 5 or enhanced category 5 cabling preferred for all new installations.