RJ11 connector and telephone interface details
RJ11 is a universal telephone connector. In fact, it was originally a common name for a connector developed by Western Electric Company in the United States. Its original name was WExW and its shape was 6 pins.
The name RJ stands for Registered Jack, which is derived from the Universal Service Ordering Codes (USOC) of Bell system. USOC is a series of Registered jacks and their connection modes. Developed by Bell Systems to connect users' devices to public networks, it is now regulated by FCC documentation.
RJ11, RJ14 and RJ25 are the same series with the same size, 9.5mm wide, but the number of contacts is different. RJ11 has only one middle contact that can connect to a pair of lines, representing a 6P2C (six posiTIon, two conductor). RJ14 uses four middle contacts to connect two pairs of wires, denoted as 6P4C; RJ25 uses all six contacts and can connect three pairs of wires, denoted 6P6C.
Here is the sequence and color table of the series:
RJ11 can also be used as an RS-232 or 485 interface. Here are three examples:
Sometimes this connector can be used to provide low-voltage power supply (AC or DC). PIN2 and PIN5(black and yellow lines) are commonly used.
RJ11 is generally used as the general term for this 9.5mm series, and RJ11-6P2C, RJ11-6P4C and RJ11-6P6C are used to distinguish the number of contacts, respectively.
The phone also uses a connector for connecting the phone and the handle, called 4P4C (also known as RJ22, and a series with RJ9 and RJ10). It has 4 contacts, 7.5mm wide, smaller than RJ11.
The connection between MIC and headset is shown in the following figure:
The connector is also used in the Apple Macintosh to connect the mainframe to the keyboard, and is also used in DirecTV set-top boxes.
RJ11 is the standard telephone connector in the US, while the BS 6312 in the UK, F-010 in France, TAE Connector in Germany are basically similar, while the TDO-Connector in Austria and WT-4 in Poland are quite different.
One of the more commonly used RJ connectors is the RJ45 connector for Ethernet connections, 8P8C, which can be connected to four twisted pairs and is 12mm wide, slightly wider than the RJ11 series. RJ45 is also sometimes used for telephone or RS232 connections, and some people use it to transmit VGA video signals.
There is also an 8P8C connector called RJ61 for connecting twisted pair pairs with the following sequence:
Because the third and fourth twisted-pair lines in the sequence are far away from each other, it will cause large crosstalk, which is not suitable for the transmission of Ethernet high frequency signals.
There is also an RJ48 CONNECTOR, also 8P8C, which can be used to connect four pairs of T1 data links, each of which can transmit 23 TDM channels.