Most people can easily identify between an RJ11 and an RJ45 wiring, and point out the differences and specific uses of each. But when it comes to an RJ45 and an RJ48, it becomes a little bit more difficult. This is because they usually use the same modular connector and the differences between the two are not easily identifiable. RJ which stands for registered jack does not actually identify the type of connector that is being used. Instead, it identifies the wiring that is being used. These two RJ types therefore differ only in how they are wired.

Both RJ48 and RJ45 use the 8P8C modular plug and 2 pairs of the wires, one pair for transmitting and one pair for receiving data. The RJ45 that we are already very familiar with uses the pins 1,2,3, and 6 for receiving and transmitting data. With RJ48, there are a few configurations that can be used depending on the situation and how they are to be used. One configuration uses the pins 1,2,4, and 5 while another uses 1,2,7, and 8. Other wires are also used for extra shielding while the remaining wires are reserved in case some uses would arise in the future.

RJ45 is used mainly in local area networks where the distances between each network element is relatively short. This is very common in a lot of offices and homes and is the main reason why it has become very popular. RJ48 is used in other applications, the most common one would be in T1 data lines where the wires can extend longer distances and are often exposed to the environment. To protect the integrity of the signal, RJ48 wirings use STP or Shielded Twisted Pair cables. RJ45s use the more common UTP or Unshielded Twisted Pair that have categories 1 to 6, with cat5e being the most predominantly used.

Whether RJ45 or RJ48 is to be used is dictated by the hardware. It is no longer up to the consumer to choose. Just make sure that you wire your connectors properly to what the hardware needs so that you have a working link.

Summary:
1.RJ45 and RJ48 use the same connector
2.RJ45 differs from RJ48 in the way they are wired
3.RJ45 is predominantly used in LAN while RJ48 is more commonly seen on T1 lines
4.RJ45 is connected with UTP cable while RJ48 uses STP