Customer Premise Equipment and Application

Chapter 5

Objectives

In this chapter, you will learn to: Discuss the purpose of customer premise equipment in a

telecommunications network Identify the significant components of a modern

telephone Discuss the varieties of station equipment Explain how private switching systems integrate with both

CPE and the PSTN Describe how enhanced CPE services and applications

work and how businesses benefit from using them

Introduction to Customer Premise Equipment

Everything on the consumer’s side of the demarcation point is known as customer premise equipment (CPE), because it resides on the customer’s premises.

In telecommunications, a telephone and any connected parts are known as station equipment because in the business world, they are located at a person’s station, or desk.

Inside a Modern Telephone

Handset

Handset

Local Loop Current

Wiring

Wiring

Tip - the wire that supplies the ground (or zero charge) from the central office’s battery to the telephone.

Ring - the wire that carries a negative charge (-48 V) from the central office’s battery to a telephone. In other words, the ring is the wire that carries signals.

Hybrid coil - introduced into telephone sets to separate the incoming transmit and receive signals into their own two-wire connections.

Wiring

Ringer

The device that sounds a bell or tone to indicate an incoming call.

Ringing tone/ringback - the tone created by the combined frequencies of 440 Hz and 480 Hz.

Distinctive ringing - a unique ringing sound or cadence for different types of calls.

Dialer

Rotary dialing - a user chooses a number and turns a wheel from that number to the finger stop then releases the wheel.

Touch-tone dialers - operate by transmitting a combination of two frequencies each time a button is pressed. Pressing each button issues a different combination of frequencies.

Dialer

Dialer

Station Protection

Station Protection

Pay Telephones

Telephones provided for public use that require coin, collect, or credit card payment to complete calls.

COCOT (customer-owned coin-operated telephone) - the name commonly used in the telecommunications industry to refer to a pay phone.

Totalizer - determines what type of coin was deposited and relays the information to the switch through pulses of brief, dual-frequency tones.

Pay Telephones

Cordless Telephones

Telephones that can be used without a physical connection to a telephone set, but still rely on a stationary telephone, or base station, to connect to the PSTN.

The main drawback to cordless phones is the ease with which signals can be picked up by eavesdroppers.

Spread spectrum transmission - signals are separated and distributed over a wide range of frequencies.

Cordless Telephones

TTY and TDD

TTY (TeleTYpewriter) - a device invented by the Teletype Corporation that uses alphanumeric characters entered through a keyboard to communicate over a voice or data network.

TDD (Telecommunications Device for the Deaf) - a specially designed device that uses a TTY and a terminal or computer screen to help speech and hearing-impaired people communicate over the PSTN.

TDDs can use relay centers, or call centers with operators who translate the typed input for the nonhearing-impaired party and type responses for reception by the hearing-impaired party’s TDD.

TTY and TDD

Key Telephone Systems

A system that gives all telephone users within an organization centralized access to one of many incoming PSTN lines.

A KTS typically consists of a wall-mounted control console that connects to the organization’s internal phones and to the telephone company’s end office.

This console, called a key service unit (KSU), signals the telephone attendant about incoming calls, controls busy indica-tor lights on line buttons, and tracks call information, among other tasks.

Key Telephone Systems

Key Telephone Systems

Key Telephone Systems

Features of electronic KTSs include: Call forwarding Caller identification Direct inward dialing Do not disturb Message waiting Music on hold Station restriction Voice mail

Private Branch Exchange (PBX)

A switch owned and operated by a business or other private organization that connects multiple telephone sets to one or more of the telephone company’s central offices.

Provides call setup and routing within an organization.

Whereas a KTS depends on a CO for dial tone, a PBX actually provides its connected telephones with dial tone.

A PBX can connect an organization to the PSTN through a trunk, a connection with significantly more bandwidth than a local loop which serves to directly connect switches.

Private Branch Exchange (PBX)

Components of a PBX

A PBX consists of four significant elements: Station lines - the lines that connect individual telephone

sets to the switch.

Central processor - the computer that oversees all PBX operations, including processing incoming calls, outgoing calls, call setup, routing, supervision, and data gathering

Switching module - The equipment that accomplishes call setup, routing, and supervision, just as a switch in a central office does.

Trunks - The lines that connect the switch to COs.

Components of a PBX

Features Offered by a PBX

Automatic call distribution (ACD) Automated route selection (ARS) Computer-telephony integration (CTI) Power failure provisions Station message detail recording (SMDR) System management Trunk queuing Unified messaging Wireless capabilities

Centrex Systems

Centrex System - a switching system that provides features similar to those offered by a PBX. However, in a Centrex system, services are supplied from the LEC’s central office.

Prevents an organization from having to purchase and maintain its own switching equipment.

Business’s lines are separated from other PSTN lines at the LEC’s CO so that only the subscribing business can use them.

Call Accounting

The process of collecting call information in a database format and making it available through a user interface, such as a software program.

For each outgoing call, a call accounting system can record: Who initiated the call (from what extension) The number and identification of the called party How the call was dialed and routed Whether the call was completed How long it took to complete the call Whether the call was local or long distance How long the call lasted How much the call cost

Automatic Call Distribution (ACD)

A method of distributing incoming calls evenly over multiple stations, according to quantity of calls handled, free time, or availability.

Answers an incoming call, then analyzes information about the call.

ACDs can also generate information about calls, including how many were sent to a queue, how long the callers waited in the queue, and whether they hung up before the ACD could forward their call to an operator.

Computer Telephony Integration

Significant call control functions that CTI enables, include: Automatic dialing from a PC interface Call screening based on incoming phone number

identification Call forwarding programmed through a simple PC

interface Automated attendant services Call logging and the collection of call accounting data

Computer Telephony Integration

Some of the significant media processing features that CTI enables include:

Voice message recording and playback Fax storing and sending Speech recognition and text-to-speech translation (for

instance, your CTI-enabled computer could read an e-mail message to you)

Online call recording

Computer Telephony Integration

Some of the customer data management features that CTI enables include:

Access to personal phone books saved on the network

Caller database records that appear when a number is selected from the phone book

Retrieval of customer calling patterns and billing information

Access to customer schedules

Computer Telephony Integration

Interactive Voice Response (IVR)

Enables individuals to provide and retrieve information to and from a computer through a touch-tone phone.

Saves money by allowing customers to help themselves rather than speak to a person and ask questions.

May provide information, accept information from a customer allow the customer to help direct his call through a series of options, or allow the caller to choose to speak with an operator.

Voice Mail

Two categories of voice mail: Standalone: may consist of a service supplied

by a LEC’s CO or it may be a separate device, similar to an answering machine, connected to one or more station lines.

Integrated: one that is connected with a private switching system through a direct cable, similar to the way in which a CTI computer connects with a private switching system.

Summary

Customer premise equipment includes telephones, modems, fax machines, answering machines, and so on. It may or may not be owned by the customer.

Touch tone, or simply tone, dialers operate by transmitting a combination of two frequencies each time a button is pressed.

In the telecommunications industry, a pay telephone is more commonly called a COCOT (customer-owned coin-operated telephone).