What type of cable in which wiring is used for telephone systems and Ethernet LAN?

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Ethernet vs. Phone Cables – What’s the Difference?

The end of an RJ45 Ethernet connector (left) vs. an RJ12 phone connector (right)

Ethernet and telephone cables look fairly similar and it is not uncommon to get the two mixed up. The key difference between the two is the size of the plastic connectors on the ends of the cable. Telephones use an RJ11/RJ12 connector whereas Ethernet uses RJ45. RJ11/RJ12 only uses 4-6 pins whereas RJ45 uses 8 pins. As a result, RJ11/RJ12 is physically smaller than RJ45 since it does not need to contain as many pins.

Modular Connectors

Both Ethernet and telephone cables are made using modular connectors. These are connectors that were designed to be used with registered jack (RJ) twisted-pair cables. The original modular jacks were invented by AT&T in the 1960s and used for some telephones. Over time they caught on and eventually became industry-standard in the 1970s.

Each type of modular connector has an RJ designation, but can also be referred to as “#P#C”. The first number is the number of metal pins (P) inside the connector. The second number is how many of those pins are actually connected to wires. Connected pins are called contacts (C). Modern telephones use either RJ11 (6P4C) or RJ12 (6P6C). Having more wires inside the telephone cable allows more signal pairs to run through a single cable, such as having a telephone and fax machine both hooked up through one line. The extra number of wires in the newer RJ12 also makes it backward compatible with RJ11 (on the flipside, RJ11 is not forward compatible with RJ12).

Because data signals are more complex than telephone signals, these older jacks did not cut it for Internet usage once the World Wide Web was invented. RJ45 (8P8C) was developed to use four pairs of wires for just that purpose. Since an extra pair of wires is needed, RJ45 connectors are physically bigger than RJ11/RJ12. While there are a few different kinds of Ethernet available, they all use RJ45 connectors in their construction. Checking the size and counting the number of pins in a connector are the easiest ways to see whether a cable is an Ethernet or telephone cord.

Other Telephone Connectors (RJ22)

While RJ11/RJ12 is the most common kind of phone cable, it is not the only type available. RJ11/RJ12 cables are used to connect phones and fax machines to wall outlets. However, they will not work when connecting a handheld receiver to the base of the telephone. Coiled handset cords are made using RJ22 (4P4C) connectors, which are even smaller than RJ11/RJ12. Since these cords do have a tendency to wear out and become damaged over time, using a cord detangler is recommended in order to prevent the cord from wrapping around itself and speeding up wear-and-tear.

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Network Media Types

Upon completing this chapter, you will be able to:

• Describe the primary types and uses of twisted-pair cables

• Describe the primary types and uses of coaxial cables

• Describe the primary types and uses of fiber-optic cables

• Describe the primary types and uses of wireless media

• Compare and contrast the primary types and uses of different media

Network media is the actual path over which an electrical signal travels as it moves from one component to another. This chapter describes the common types of network media, including twisted-pair cable, coaxial cable, fiber-optic cable, and wireless.

Twisted-Pair Cable

Twisted-pair cable is a type of cabling that is used for telephone communications and most modern Ethernet networks. A pair of wires forms a circuit that can transmit data. The pairs are twisted to provide protection against crosstalk, the noise generated by adjacent pairs. When electrical current flows through a wire, it creates a small, circular magnetic field around the wire. When two wires in an electrical circuit are placed close together, their magnetic fields are the exact opposite of each other. Thus, the two magnetic fields cancel each other out. They also cancel out any outside magnetic fields. Twisting the wires can enhance this cancellation effect. Using cancellation together with twisting the wires, cable designers can effectively provide self-shielding for wire pairs within the network media.

Two basic types of twisted-pair cable exist: unshielded twisted pair (UTP) and shielded twisted pair (STP). The following sections discuss UTP and STP cable in more detail.

UTP Cable

UTP cable is a medium that is composed of pairs of wires (see Figure 8-1).UTP cable is used in a variety of networks. Each of the eight individual copper wires in UTP cable \is covered by an insulating material. In addition, the wires in each pair are twisted around each other.

UTP cable relies solely on the cancellation effect produced by the twisted wire pairs to limit signal degradation caused by electromagnetic interference (EMI) and radio frequency interference (RFI). To further reduce crosstalk between the pairs in UTP cable, the number of twists in the wire pairs varies. UTP cable must follow precise specifications governing how many twists or braids are permitted per meter (3.28 feet) of cable.

UTP cable often is installed using a Registered Jack 45 (RJ-45) connector (see Figure 8-2). The RJ-45 is an eight-wire connector used commonly to connect computers onto a local-area network (LAN), especially Ethernets.

When used as a networking medium, UTP cable has four pairs of either 22- or 24-gauge copper wire. UTP used as a networking medium has an impedance of 100 ohms; this differentiates it from other types of twisted-pair wiring such as that used for telephone wiring, which has impedance of 600 ohms.

UTP cable offers many advantages. Because UTP has an external diameter of approximately 0.43 cm (0.17 inches), its small size can be advantageous during installation. Because it has such a small external diameter, UTP does not fill up wiring ducts as rapidly as other types of cable. This can be an extremely important factor to consider, particularly when installing a network in an older building. UTP cable is easy to install and is less expensive than other types of networking media. In fact, UTP costs less per meter than any other type of LAN cabling. And because UTP can be used with most of the major networking architectures, it continues to grow in popularity.

Disadvantages also are involved in using twisted-pair cabling, however. UTP cable is more prone to electrical noise and interference than other types of networking media, and the distance between signal boosts is shorter for UTP than it is for coaxial and fiber-optic cables.

Although UTP was once considered to be slower at transmitting data than other types of cable, this is no longer true. In fact, UTP is considered the fastest copper-based medium today. The following summarizes the features of UTP cable:

• Speed and throughput—10 to 1000 Mbps

• Average cost per node—Least expensive

• Media and connector size—Small

• Maximum cable length—100 m (short)

Commonly used types of UTP cabling are as follows:

• Category 1—Used for telephone communications. Not suitable for transmitting data.

• Category 2—Capable of transmitting data at speeds up to 4 megabits per second (Mbps).

• Category 3—Used in 10BASE-T networks. Can transmit data at speeds up to 10 Mbps.

• Category 4—Used in Token Ring networks. Can transmit data at speeds up to 16 Mbps.

• Category 5—Can transmit data at speeds up to 100 Mbps.

• Category 5e —Used in networks running at speeds up to 1000 Mbps (1 gigabit per second [Gbps]).

• Category 6—Typically, Category 6 cable consists of four pairs of 24 American Wire Gauge (AWG) copper wires. Category 6 cable is currently the fastest standard for UTP.

Shielded Twisted-Pair Cable

Shielded twisted-pair (STP) cable combines the techniques of shielding, cancellation, and wire twisting. Each pair of wires is wrapped in a metallic foil (see Figure 8-3). The four pairs of wires then are wrapped in an overall metallic braid or foil, usually 150-ohm cable. As specified for use in Ethernet network installations, STP reduces electrical noise both within the cable (pair-to-pair coupling, or crosstalk) and from outside the cable (EMI and RFI). STP usually is installed with STP data connector, which is created especially for the STP cable. However, STP cabling also can use the same RJ connectors that UTP uses.

Although STP prevents interference better than UTP, it is more expensive and difficult to install. In addition, the metallic shielding must be grounded at both ends. If it is improperly grounded, the shield acts like an antenna and picks up unwanted signals. Because of its cost and difficulty with termination, STP is rarely used in Ethernet networks. STP is primarily used in Europe.

The following summarizes the features of STP cable:

• Speed and throughput—10 to 100 Mbps

• Average cost per node—Moderately expensive

• Media and connector size—Medium to large

• Maximum cable length—100 m (short)

When comparing UTP and STP, keep the following points in mind:

• The speed of both types of cable is usually satisfactory for local-area distances.

• These are the least-expensive media for data communication. UTP is less expensive than STP.

• Because most buildings are already wired with UTP, many transmission standards are adapted to use it, to avoid costly rewiring with an alternative cable type.

Which type of cable is used for telephone cables?

What type of cable is used for LAN?

What type of UTP cable in which wiring is used for telephone systems and Ethernet LAN cat5 cat5e cat3 cat6?