Telephone Jack VS Ethernet Jack: What’s The Difference?

Last Updated on July 18, 2022

Whether you want an ethernet or telephone cable for your connections, the most important thing is a good signal. You can use telephone jacks or ports and Ethernet jacks to connect devices to a network, but each has unique qualities, and you may be trying to compare telephone jack vs ethernet jack. Here is your answer

The key difference between these two is that

  • The telephone jack connects a telephone to a wall outlet, while the ethernet jack connects computers and other devices to an Ethernet cable. They look the same but have different uses. 
  • The ethernet jack accepts an RJ45 connector, while the telephone jack accepts RJ11 and RJ12 connectors. 

In this article, I’ll outline the differences between the two jacks and how you can explore their functionalities. 

Key Specs Telephone Jack

Ethernet Jack

Function Voice communication Data transmission
Installation Mounted on walls Found in computers, smart TVs, etc. 

Also mounted on walls.

Size 3.5mm 5.8mm
Connectivity Has RJ11, and RJ12 connectors Have RJ45 connectors
Conductivity Uses 4 or 6 conductors Uses 8 conductors
Cabling Accepts phone cables Accepts ethernet cables
Price About $6 (Less Expensive) About  $10 (More Expensive) 
Connector Size Physically smaller Physically bigger
Convertibility Can be converted to an Ethernet jack Cannot be converted to a phone jack
Transmission speed Has a lower speed Has a faster speed
Bandwidth Has a smaller bandwidth Has a larger bandwidth
Plug The plug is flat and small The plug is thick and round

What Is A Telephone Jack?

A telephone jack is a modular connector that lets you connect your phone line to an electrical outlet. The telephone jack accepts two cables and has two parts: the plug and the socket. The plug has a blade-like shape and fits into your phone’s port. 

The socket is a hole in the wall where you can insert the plug from your phone line. Most homes in North America have at least one telephone jack in the wall near their telephone. 

They’re usually located next to each other in a small plastic box on the wall. This box is called a “telephone outlet” or “telephone junction.” 

Although it’s designed for voice communications, you can convert the telephone jack into an ethernet jack.

What Is An Ethernet Jack?

An ethernet jack or LAN port is a socket that allows you to connect your computer to a network. It’s used mainly for connecting to the internet, but you can use it for local area networks (LANs). The cable has eight wires that carry data from your computer to the network. 

The plug on the end of the line is called an RJ45 connector, and it looks like a telephone jack but is slightly bigger. Desktop computers and laptops often come with in-build ethernet jacks for internet connectivity. 

The inbuilt Ethernet jack is connected to the computer’s ethernet card, which is attached to the motherboard. You can find them on walls in modern houses.

Telephone Jack VS Ethernet Jack | Differences

The main difference between an Ethernet jack and a telephone jack is that one is designed for connecting computers. In contrast, the telephone jack is designed for connecting telephones or using a telephone cable. Other differences are:

  • Telephone jack connectors (RJ11 and RJ12) have 4 or 6 pins depending on the connection type. The 4-pin version connects two devices, while the 6-pin version can connect more than two devices in a series.
  • The ethernet jack is found in computers, servers, and smart TVs and has 8 pins. It has different speeds ranging from 10 Mbps and 100 Mbps. Gigabit ethernet has a speed of 1,000 Mbps. 
  • The two types of jacks are not interchangeable, but it is possible to convert one into the other using adapters purchased at most electronics stores. The process does not require special tools but takes time and skill.


Ethernet jacks are used for network connections on smart devices like computers, servers, etc., or in a building. 

The telephone jack is used for connecting phone line sets in a building. It is for voice communication.

The two types of jacks are not interchangeable, but it is possible to convert one into the other using adapters purchased at most electronics stores.


Telephone jack connectors (RJ11 and RJ12) have 4 or 6 pins depending on the connection type. The 4-pin version connects two devices, while the 6-pin version can connect more than two devices in a series.

Ethernet jacks have RJ45 connectors consisting of 8 pins. This nature allows them to transmit data signals.


The ethernet jack is found in computers, servers, and smart TVs. You can also install them on walls.

You can only install a telephone jack on walls in homes or offices.


Telephone jacks look similar to ethernet jacks, but the sizes are different. An ethernet jack is larger because it has 8 pins. Telephone jacks have 4 or 6, so they’re smaller.


The telephone jack coupler is cheaper than ethernet jack couplers, but they’re not expensive. You can find an RJ11 coupler at just $6, but an ethernet jack comes at $10.

Can You Use The Telephone Jack For The Internet?

You can use the phone jack for internet connection only if you have a modem that supports it. The DSL modem allows you to convert the telephone jack into an ethernet jack which you can then connect to your computer. 

Another way is by joining an RJ45 connector to the phone jack, a simple DIY.

How To Convert A Telephone Jack To An Ethernet Jack

If you are trying to switch from a telephone to an ethernet jack, follow the step-by-step method below:

Method 1: Using DSL Modem

A DSL modem is a device that connects to your computer via an Ethernet cable and provides you with access to the internet. The DSL modem is connected to your local telephone service provider, providing you with Internet access on your computer.


  • Connect the DSL modem to power by plugging the electric DSL’s power supply cord into the wall socket.
  • Insert the plug at one end of the modular telephone cord into the telephone jack socket.
  • Insert the other end into the socket labeled “DSL” on the back of the DSL modem.
  • Insert the ethernet plug at one end of the ethernet cable into the socket labeled network at the rear of the DSL modem.

Method 2: Changing The Connector

The old RJ11 phone jacks you probably have in your home are getting replaced by the new RJ45 ethernet jacks. 

  • You’ll need a data connector that converts the old telephone jack into an Ethernet jack. You can get one at your local electronics store or on Amazon.
  • Use a screwdriver to remove the wall panel covering the telephone jack. 
  • Pull out the phone cable; it’s likely a Cat5, Cat5e, or Cat6 cable; you can tell from the colors.
  • Match the colors on the telephone wire(s) to the colors on the data connector and insert them into their slots.
  • Cut off loose ends and reinsert the cable.
  • Reinstall the wall panel.

So, what is the difference, and which should you go for?

Answering the question of telephone jack vs ethernet jack, which you should go for, is not so complex. It depends on what you hope to achieve. 

The ethernet jack is perfect for internet connections, while a telephone jack is ideal for a telephone connection.

If you built your house over 50 years ago, you’d have a telephone jack(s) on your walls. You can convert them into ethernet jacks and use them for internet connections. Alternatively, install an RJ45 jack on your wall.

You May Want To Know

Can You Plug An Ethernet Cable Into A Phone Jack?

You cannot plug an ethernet cable directly into the telephone jack because it is not wired for telephone service. You can plug an Ethernet cable into a DSL, cable modem, or even your router if it has an Ethernet port.

The problem with using a phone jack for internet access is that it’s not meant for that purpose. The phone cable has a low bandwidth, so it cannot send high-speed internet traffic.

What Is A Telephone Wall Jack Called?

The telephone wall jack is called Registered Jack in the US. It’s why we have RJ11, RJ12, and RJ45. The Federal Communications Commission licenses the phone jacks. 

Most telephones in the United States are connected to the wall via a four-pin RJ11 plug, which plugs into the telephone wall jack. 

Are RJ11 And RJ45 Connectors Different?

RJ11 connectors are used for telephone wires and have four pins. RJ45 connectors are used for Ethernet networks and have eight pins. Both types of connectors come in male and female versions.

Where Is RJ45 Used Besides Ethernet Jack?

RJ45 is found on most computers and networking devices with ethernet jacks and other applications where twisted pair cables are required. 

For example, it’s often used in telephone systems and audio/video installations because these applications require twisted pair cabling for maximum performance.

Is RJ11 Better Than RJ12 For Telephone Jack?

RJ11 and RJ12 are two types of jacks that are used in telephone networks, but RJ11 is an older version. RJ12 is backward compatible with RJ11 and is suitable for centralized telephone networks as common in offices. RJ11 is suitable for home telephone communications.