There are mainly two types of cable connectors used for twisted pair connection in voice and data communication installation.
RJ11 connectors typically have only 6 positions and 4 or 2 contacts. They are not internationally standardized, but used to be a very popular choice for both commercial and residential telephone applications due to their simplicity and small forms.
RJ45 connectors normally have 8 positions and 8 contacts. Therefore, RJ45 connectors are larger than RJ11 connectors in forms. An RJ45 connector is usually used for data transmission in scenarios such as monitoring projects and general cabling in the equipment room. It is an indispensable supporting role in Ethernet and is generally used at both ends of a network cable to connect various network devices, such as computers, routers, switches, etc.
Notice: Due to the different structure of RJ45 and RJ11 connectors, the wiring sequence standard and applications are also different. It is not recommended to use RJ11 plugs for RJ45 jacks as it may cause damages on the devices.