Wired networks for telephony and more, like Internet access.
Voice communications over copper lines - plain old telephone system (POTS) or public switched network system (PSTN)
"PSTN (public switched telephone network) is the world's collection of interconnected voice-oriented public telephone networks, both commercial and government-owned. It's also referred to as the Plain Old Telephone Service (POTS)." [searchnetworking.techtarget.com]
"The public switched telephone network (PSTN) is the aggregate of the world's circuit-switched telephone networks that are operated by national, regional, or local telephony operators, providing infrastructure and services for public telecommunication." [wikipedia]
"Plain old telephone service (POTS) is a retronym for voice-grade telephone service employing analog signal transmission over copper loops.[1] POTS was the standard service offering from telephone companies from 1876 until 1988[2] when the now-obsolete Integrated Services Digital Network (ISDN) Basic Rate Interface (BRI) was introduced, followed by cellular telephone systems, and Voice over IP(VoIP)." [wikipedia]