Cabling
RJ11
Also known as: Phone Jack, Telephone Jack, 6P2C
The small 6-pin connector used for telephone lines — narrower than an RJ45 Ethernet jack and wired for voice rather than data.
RJ11 connectors use a 6P2C configuration (6 positions, 2 contacts in standard use) and are the universal connector for analog phone lines in North America. They're visually similar to RJ45 but noticeably narrower — you can insert an RJ11 into an RJ45 jack in a pinch (it'll fit the center pins) but it's not a proper connection.
In a modern office context, you'll encounter RJ11 primarily at analog phone handsets, DSL modems, and legacy fax machines. With VoIP adoption, dedicated analog phone wiring is increasingly rare in new installations — most modern phone systems run over Ethernet to IP handsets.
The RJ12 variant uses the same physical form factor as RJ11 but wires all six contacts, commonly used for multi-line phones and PBX systems.