Know the Difference Between RJ45 Port and RJ11 Port

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Right from the good old days of analog telephones and faxes, cables and connectors have been an integral part of network communication. With the advancements in electronics, internet technologies, and the importance of data communication apart from voice, the demand for private business networks, and subsequently the required devices has only grown. RJ11 jack and RJ45 jack connectors have been there for a very long time, and in fact RJ45 is still used in copper cable data communication networks. RJ basically stands for Registered Jack, and as the numbers in the terms imply, RJ11 is much older than the later. The numbers 11 and 45 are the interface standards. This post compares RJ45 vs RJ11 connectors and more.

fiber optic modem

What is a Registered Jack?

RJ stands for registered jack. These jacks serve as an interface for telecommunication as well as data networks. They connect voice or data devices to a central router or modem, especially in small sized networks. In large networks, they are used with the help of switches. Any RJ45 connector has male and female versions. Male parts are the plugs on Ethernet cable ends, while female parts are the sockets on devices. Mostly, Ethernet cables used in networks are eight strands of wires that are paired, which means there are four sets of twisted wire strands. This wiring is based on 8P8C configuration, wherein P stands for position and C stands for contact. The standard wiring used for the functioning of RJ45 network connectors is T568A or T568B. Both these standards have different types of connectivity and are color coded accordingly. The male connector has pinout locations wherein all these eight strands of Ethernet cable must be connected accurately for the correct functioning. With the help of these connectors, you can simply plug in a device directly into a modem or router for internet connectivity. This is especially useful when working on standalone computers.

What is RJ45 and RJ11?

The following pointers on RJ11 and R45 cable connectors will help you understand it better.

  • RJ11:
    RJ11 as discussed before was widely used in analog telephony to connect the phone instrument and the cable. Now it is mostly used to connect to modems and is still used in landlines. It is a 4-slot connector and has six pins, which means you cannot fit it into an RJ45 slot. It is used in PSTN telephone lines to connect telephone cables which are technically different from Ethernet cables.
  • RJ45:
    Unlike RJ11, these connectors are used for both telecom and data networks. RJ-45 connectors have 8 pins and these are typically used to connect Ethernet cables to a switch or serial data modem. You would commonly find switches with RJ45 connectors in copper cable networks. Some switches have RJ45 as well as SFP fiber ports and hence these can be used in fiber networks as well. So, these are typically used for data communication networks where IP voice telephony may also be there. As mentioned, there are male and female connectors. Here are the details.
  • Male connectors:
    These are plug-in devices located on the other end of the Ethernet cable. They may be shielded in metallic enclosures which helps reduce EMI and retain signal strength. These can be used to increase the cable length which may be required for long distance data transmissions. All you need to do is connect a male to male adapter. This saves on buying a long cable and wiring work associated with it. Male connectors with special IP ratings are designed for heavy duty applications and can resist dust, moisture, vibration, and so on.
  • Female connectors:
    These are the recessed sockets, wherein the male plug is inserted. Also known as female jacks, they can be mounted on walls or panels, or embedded into the connected device.

What are the Applications of RJ45Port?

RJ45 ports have numerous applications in modern networking and communication setups. These versatile ports are widely used in various industries and environments due to their ability to provide reliable and high-speed data transfer. Here are some of the key applications of RJ45 ports:

  • Ethernet Networking: RJ45 ports are predominantly used for Ethernet networking, enabling devices to connect to Local Area Networks (LANs) and Wide Area Networks (WANs). They serve as the primary interface for wired network connections in homes, offices, data centers, and educational institutions.
  • Internet Connectivity: In homes and offices, RJ45 ports are commonly used to connect computers, laptops, gaming consoles, smart TVs, and other network-enabled devices to the internet. They allow users to access online resources, browse the web, and stream media.
  • Data Transfer: RJ45 ports facilitate high-speed data transfer between devices within a network. They are essential for sharing files, documents, multimedia content, and large data sets across connected devices.
  • VoIP (Voice over Internet Protocol) Phones: Many VoIP phones and IP-based communication systems use RJ45 ports for voice communication over the internet. These ports enable reliable voice calls and conferencing services.
  • IP Cameras and Security Systems: RJ45 ports are commonly used to connect IP cameras and security devices to the network. This allows for remote monitoring and management of security systems.
  • Network Switches and Routers: RJ45 ports are found on network switches and routers, allowing multiple devices to connect to the network simultaneously. They play a crucial role in directing data traffic and ensuring efficient network operation.
  • Printers and Network-Enabled Peripherals: Many network-enabled printers and peripherals feature RJ45 ports, enabling users to access and use these devices over the network.
  • Smart Home Devices: With the rise of the Internet of Things (IoT), many smart home devices, such as smart thermostats, smart speakers, and smart appliances, use RJ45 ports for internet connectivity and communication.
  • Industrial Applications: RJ45 ports are also utilized in industrial settings for networking industrial equipment and machines, enabling seamless data exchange and monitoring.
  • Video Conferencing Systems: RJ45 ports are used in video conferencing systems, facilitating high-quality video and audio communication over the internet.
  • Gaming Consoles and Online Gaming: Many gaming consoles use RJ45 ports for wired internet connections, offering stable and low-latency online gaming experiences.
  • Media Servers and NAS (Network-Attached Storage) Devices: RJ45 ports are common on media servers and NAS devices, allowing users to access and stream media content from various devices.

What is the difference between RJ45 and RJ11?

Here are some pointers regarding the major differences between RJ45 and RJ11:

  • Physical appearance: The primary difference lies in their physical appearance, wherein the RJ45 connecter is broader than RJ 11 and has 8 pins. RJ112 has 6 pins and a narrow plugging end. Their pin colors are different as well.
  • Bandwidth: Since RJ 45 is used in data communication networks using Ethernet cables, it supports 10Gbps bandwidth. This can be further extended using fiber optics such as a fiber cable and a fiber media converter. RJ11 support just 24Mbps bandwidth.
  • Position and contact: Since RJ45 has 8 pins and connecting ports, it is called 8P8C. On the same lines RJ11 is called 6P4C.
  • Cable type: RJ45 connectors commonly connect to Cat5 and Cat6 cables, while RJ11 simply connects to a telephone cable.
  • Device connectivity: RJ45 can connect to various devices in a copper cable network such as switches, cables, computers, routers, and so on.
  • Sockets and ports: Switches with RJ11 connectors comprise mainly two sockets for a 2-line telephone system. On the other hand, switches with RJ45 connectors are of various types such as managed switches or unmanaged network switches 4,5, 8, 10 or even 20 ports. Some switches support fiber connections as well and hence have SFP+ ports on one end and RJ45 on the other. The number of ports may vary.
  • Flexibility: RJ45 connectors are definitely more flexible than RJ11. One cannot connect an RJ11 connector to an RJ45 compatible device, port, or interface; however, RJ45 connectors are backward compatible and suitable for RJ11 based analog telephony devices.
  • Shape and size: RJ11 connectors are square shaped and typically small and compact. RJ45 connectors are long and mostly rectangular. Also, they need to accommodate more number of wires than the former.

Do you have an existing legacy network which you plan to expand in terms of transmission distance and speed? If yes, it would be wise to blend fiber optics into your existing copper cable network. However, ensure you source all the network devices from a certified and reliable manufacturer and supplier. VERSITRON offers several network devices compatible with copper as well as fiber networks. The company offers Fiber Optic network switches and fiber media converters with RJ45 ports for copper as well as SFP+ ports for fiber.


Q. What is the function of RJ45?
The function of RJ45 connectors is to provide high-speed data transfer and networking capabilities. They are the standard interface for wired Ethernet connections, enabling fast and reliable data communication in Local Area Networks (LANs) and Wide Area Networks (WANs).

Q. Is RJ45 used for internet?
Yes, RJ45 connectors are commonly used for internet connections. They support high-speed data transfer, making them essential for reliable and fast internet access in homes, offices, data centers, and various other networking environments.

Q. Is RJ45 faster than Wi-Fi?
RJ45 (wired Ethernet) connections are faster and more reliable than Wi-Fi (wireless) connections. Wired connections through RJ45 offer higher data transfer speeds and lower latency since they are not susceptible to signal interference or distance limitations, resulting in more consistent and faster data transmission.

Q. Does RJ45 have speed limit?
Yes, RJ45 connections have speed limits based on the category of Ethernet cable used. The most common categories are Cat5e, Cat6, and Cat6a. Cat5e cables support speeds up to 1 Gbps, Cat6 cables up to 10 Gbps, and Cat6a cables up to 10 Gbps over longer distances.

Rich Tull

Rich Tull
R.W. Tull is the President of Versitron, a leading technology company specializing in data communication and networking solutions. With expertise in Guiding network switches and media converters, R.W. Tull has played a pivotal role in driving Versitron's success. His deep understanding of these technologies has enabled the company to provide innovative and reliable solutions to clients. As a visionary leader, He ensures that Versitron remains at the forefront of the industry, delivering cutting-edge networking solutions that enhance data communication efficiency.
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