RJ11 vs RJ45 Connectors: Size, Pins, and What Each One Is Used For

RJ stands for Registered Jack. Both RJ45 and RJ11 are registered jack connector types used in home and office networks, but they serve different purposes. RJ45 is the standard connector for Ethernet networking, while RJ11 is used for telephone lines and digital subscriber line (DSL) modem connections. The two connectors differ in pin count — the metal contacts inside the connector that carry the signal. This page walks you through identifying each connector type and where to find them on a TP-Link modem router.

Key Takeaways

• RJ45 connectors have eight positions and up to eight conductors and are used for Ethernet networking to connect routers, switches, and cable or fiber modems.
• RJ11 connectors have six positions and up to four conductors and are used for telephone lines and ADSL/VDSL modem connections.
• RJ45 connectors are larger than RJ11 — approximately 6mm x 11mm compared to 6mm x 9.5mm for RJ11.
• An RJ11 connector can physically fit into an RJ45 port, but this will not work and may damage the RJ45 port.
• On a TP-Link modem router, RJ11 ports connect to the telephone or DSL line, while the yellow RJ45 ports connect Ethernet devices.

RJ11 vs RJ45 Connectors

RJ stands for Registered Jack.

RJ45

• 8 Position
• 8 Pin/Conductor (4/8 options)
• Mainly used in network wiring.
• 6mm * 11mm

RJ45 connector (male)

RJ45 Jack (female)

RJ45-plug-jack-schematic

RJ11

• 6 Position
• 4 Pin/Conductor (2/4/6 options)
• Used for telephone, (ADSL/VDSL) modem, etc.
• 6mm * 9.5mm

RJ11 6P4C connector (male)

RJ11 6P4C Jack (Female)

RJ-11-plug-jack-schematic

RJ45 and RJ11 Ports on TP-Link Modem Routers

RJ11 & RJ45 ports on TP-Link modem Router

The first 3 ports are RJ11 (6P6C/6P4C/6P2C) Jack. These ports are normally used with an RJ11 connector (telephone line).

The 4 yellow ports are RJ45 (8P8C/8P4C) Jack. These ports are normally used with an RJ45 connector (Ethernet cable).

RJ11 vs RJ45: Comparison

Figure 8: RJ45&RJ11 Pairs Figure 9: RJ11 in real RJ45 in real

Table 1: Comparison between RJ45 & RJ11

Conclusion

• RJ45 is mostly used for Ethernet cables, while RJ11 is used for telephone units.
• RJ45 has 8 wires inside, while RJ11 has 4 wires.
• RJ45 is larger than RJ11.
• An RJ45 connector cannot be plugged into an RJ11 port. However, an RJ11 connector can physically fit into an RJ45 port — this is a common mistake that will not work and may damage the RJ45 port, as telephone lines carry power from the provider.