Telephone Cables – What You Need to Know

Registered Jack 45, Telephone Cable

This article offers an introduction to telephone cables. You will learn how they work, what they are used for and the various features available.

You would think that something as simple as a telephone cable would be pretty self-explanatory. But in truth, there is a lot more to it than just a piece of plastic. Everything from external to internal components, connectors, and shape. 

What Is A Telephone Cable?

A telephone cable can be a variety of different internal and external cables created for the purpose of connecting phone equipment. Telephone cables haven’t changed much over the years. They are one of the most basic types of cables. 

To break it down, there is a copper telephone wire that consists of strands of wire twisted together in pairs of two. The wires run inside of and are protected by an outer cable. The cables are usually gray.

A simple telephone line can connect you to the entire world. 

Telephone Cable

What Are Telephone Cables Used For?

The purpose of a telephone cable is to connect a telephone or desktop PC to a telecommunications network so they can function. They also have other uses as well.

Digital Subscriber Line (DSL)

DSL is used to send data through telephone cables. It is a higher frequency and so it can be delivered with standard telephony. Asynchronous Digital Subscriber Line (ADSL) is the most common form of DSL. It is used to provide access to internet service to business and residential customers. 

Wired Networking

While wireless is king in the world today, wired networking still holds a place of purpose. Especially in locations where Wi-Fi reception is bad, or where you want to maintain a hyper-secure connection. 

Ethernet cables are a modified version of wired telephone cabling, allowing for a faster and more reliable throughput and connection. 

The Various Features of Telephone Cables

The number of different aspects of a telephone cable is notable. We are going to touch on some of the key terminologies and features here to give you better insight.


Flat cables connect phones to the wall. The most typical connector is an RJ11 telephone cable, the standard option for connecting a single telephone to a single wall connector. 

Coiled cables connect the receiver to the phone. Coiled cable uses a different and smaller connector like an RJ9 or RJ22.

Location of Use

Internal telephone cables are used for interior locations only. These cables are very flexible and pliable. They are easy to install and route between walls and in tight spaces with ease. 

Cable that is only used outside is external telephone cable. Because it is installed outside, the external cable needs to have a thicker, durable outer casing. Thicker than interior cabling. It also needs to be weatherproof to protect from any of the elements it might encounter.

The best of both is having one cable that could work as either indoor or outdoor. This is where the combo indoor/outdoor telephone cable comes in. This cable is safe to use anywhere.

Overhead telephone cabling can be seen outdoors overhead. It is used for voice and data. Some are even used for TV signals. Overhead telephone cables are connected to the public switched telephone network. 

Data or Voice?

Straight Cable

Straight cables are primarily used for data, like a fax machine. They also feature an exact duplicate set of wires to pin connections when the other end of the cable is plugged in. For example, pin A to pin A, pin B to pin B, etc.

Reversed Cable

Used for voice, like a telephone, reversed cables feature a reverse ordered connection, or mirrored on the second side. For example, pin A to pin F, pin B to pin E. 



Telephone wire comes in two gauges, 22 gauge, and 24 gauge; 24 gauge is today’s standard. 

Connector Types

While there are many, here are the most used or well-known connector types. 

Registered Jack-11 (RJ11) 

RJ11 is the common connector used to plug a telephone into a wall jack, and handset into a phone. This is an older version of RJ12, however, RJ11 uses four internal wires. RJ11 will not work with RJ12.

Registered Jack-12 (RJ12)

The same size as RJ11, however, RJ12 uses 6 internal wires. RJ12 is backwards compatible with RJ11 (even though RJ11 will not work with RJ12).

Registered Jack-14 (RJ14)

RJ14 are used mostly to connect telephone handsets. The difference from RJ11 and RJ12, is that an RJ14 connector uses 4 wires.

Registered Jack-45 (RJ45)

RJ45 connectors are similar to the RJ11 telephone cable connectors, but use 8 pins and are a little bit bigger. 

Telephone Cable or Ethernet Cable – What’s the Difference?

Telephone and ethernet cables look very similar and it’s not hard to get the two mixed up. The main difference between the two types is the speed of voice and/or data transmission and the size of the connectors on the ends of the cable.

Telephone cables have the ability to operate a network through Frequency Division Multiplexing (FDM). This is a technique that transmits the data at a different frequency than voice traffic. Think of it kind of like a multi-lane freeway. There are multiple lanes, and each lane is used to carry a separate signal.

Ethernet cable, aka network cable, is the most common type of cable used for network connectivity. These cables can be split up into several different types including shielded twisted pairs and unshielded twisted pairs. Ethernet cables are also rated by category; Cat5e, Cat6, and Cat6a are the most common types. They can also be separated as UPC and APC. Those types of cables depend on the twisting of pairs of wires to reduce loss of signal. 

Ethernet cables have RJ45 connectors. These are similar to the RJ11 telephone cable connectors, but use 8 pins and are a little bit bigger. 

Small Cable, Big Job

Who would have thought there could be so much to learn about a simple little telephone cable? They are small, but mighty and perform the very important task of keeping people connected. 

If you want to know more about telephone cables or have any other questions about network cabling or phone systems, give Network Installers a call and we would be happy to answer any questions you have.

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The Network Installers is a low voltage electrical contractor that provides data cabling, network installation, fiberoptic installation, and WIFI installation. We've been serving commercial customers since 2008 with exceptional quality, consistency, and professionalism.


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