More commonly known as a modem port, phone connector, phone jack or phone line, the Registered Jack-11 (RJ-11) is a four or six wire connection for telephone and Modem connectors in the US.

What is a standard telephone jack called?

RJ11 The most widely implemented registered jack in telecommunications is the RJ11. This is a modular connector wired for one telephone line, using the center two contacts of six available positions.