RJ11 is a 6 position 6 connection (6P6C) Registered Jack generally used for analog telephone lines, fax lines, and modems. A true RJ11 is a 6P2C jack. Registered Jack is a standardization created to describe the physical jack as well as its wiring and specifically refers to a jack but is loosely used in the industry to refer to modular plugs as well. In 1934 when the Bell Company had a monopoly on the telephone industry, the phone company owned everything having to do with telephones. This means that Bell owned the cable, the cabling within the house and the phone itself; when they did this there was no way to connect anything to the phone line because the phones were hardwired directly to the network cable.
Because Bell owned everything there was no need to standardize cable connections for other companies to create their own products. Eventually between the efforts of two companies trying to establish their hold in the phone industry, the Carter Phone (1956) and Hush-a-Phone (1968), the US government deemed that the Bell Company did indeed have an illegal monopoly and that regulations had to be set in place in. Now the phone company only owns the cable that provides the service and because of that Bell had to come up with a universal standard for connecting the wide area network (WAN) with the local area networks (LAN) within each building. The phone company’s responsibility ends at a termination that is at a location called the Minimum Point of Entry (MPOE). It’s at the MPOE that the phone company terminates their cable then private companies create connections to that cable to enable phone and/or internet service.
Tip and Ring
Tip and ring is a term still used today and can still be seen today but originated in the early days of telephony. Back when phone networks started there was a human being operator instead of a machine. The operator would receive a call from someone within the network they were directly connected to then connect that call to a different network. The operator had two plugs to connect the phone cable called the tip and the ring, much like how there are two connections on a modern day RJ11, the tip was the grounding cable and the ring carried the voltage. Today we have routers and switches that do the job of the original human operator.
RJ11 Jack Wiring
The 6 wires in a RJ11 connector are divided into 3 pairs: the first is striped blue and white, the second is orange and white, and the third pair is green and white. The combination of these wires usually carries data or voice. A single-phone line uses only one pair of wires. A two-telephone line uses two pairs, and the third pair of wires could be used for a third line. Most dial-up computer modems are typically plugged into a RJ11 jack, whether for Internet connection or a local area network. RJ11 jacks are typically used for fax, modem, and telephone. A RJ11 plug can also be plugged into a RJ45 jack.