Before 1973, the phone company owned the wires right up to the phone on the wall, and often owned the phone as well. Then the FCC mandated that customer-provid

Before 1973, the phone company owned the wires right up to the phone on the wall, and often owned the phone as well. Then the FCC mandated that customer-provided equipment be supported, assuming it met standards. The RJ11 jack (and siblings, right up to the RJ45 for ethernet) came into widespread use after that.