RJ11 vs RJ12
The registered jack standard has been around for some time for people to follow in wiring their telephone lines. It is abbreviated into RJ and is then followed by two digits that identify the specific standard. The RJ11 and RJ12 standards are quite closely related and in fact look identical to each other to the uninitiated. This is because they both use the same six slot connector. The only difference between these two is in how they are wired and the number of the wires that are being used.
RJ12 is a 6P6C wiring standard. This means that there are also 6 wires that are terminated in the connector, occupying all the available slots. RJ11 is a 6P4C wiring standard and only has four wires connected and the remaining two slots are no longer used. Because of this, you would need to pay close attention to the cables that you are utilizing as cable used four RJ11 might not be suitable for RJ12, even if they look identical.
Despite the differences, both wiring standards are used for the same purpose, telephone lines; commonly using the center pair. But there are also other applications that make use of the RJ12 standard. Keyed telephone systems and PBXs may take advantage of the additional two connectors. Because of this, RJ12 is not really very common and only the people who have experience working with large company’s telephone systems are familiar with RJ12 wiring. RJ11, on the other hand, is relatively very common because it is used in the majority of the phone units and wiring of some telephone companies. This has even developed into the connector itself being popularly referred to as RJ11.
There is really no individual decision whether to choose RJ11 or RJ12 in your connection as this is often dictated by the telephone company that you are subscribed to. With that said the additional two lines that are made available when using the RJ12 standard can become quite handy in a PBX system where you can add extra lines on your own.
Summary:
1. RJ11 and RJ12 wiring uses the same six slot connector
2. RJ11 and RJ12 only differs in the wiring
3. RJ12 utilizes all six slots while RJ11 only uses four of the six available slots
4. RJ11 and RJ12 are commonly used for telephone systems with RJ12 being used in different configurations
5. RJ11 is very common in today’s homes while RJ12 is quite uncommon except in some large companies