An Overview of Computer Telephony

Computer Telephony Overview

Two technologies are revolutionizing the way the world communicates: telephones and computers. Telephones are everywhere. For decades, they have been prevalent in offices, public establishments, and homes. And computers are catching up. However, these two technologies historically have remained separate. Often, the only thing in common has been the desk on which they both sit. But the Computer Telephony industry has been combining the best of telephone and computer technology to let people exchange information more quickly and easily.
The power driving the Computer Telephony industry is telephone network access to computer information through almost any convenient, easy-to-use, and available terminal device, including:

Telephones (pulse dial, touch-tone, and wireless)
Facsimile (fax) machines
Personal Computers (PCs)

These terminal devices access a multi-user Computer Telephony platform that supports applications that process the information within the call and/or route and monitor the progress of the call. These functions of the Computer Telephony platform are an integral part of enterprise information systems.

Computer Telephony systems can range from simple voice mail to multi-media gateways. The equipment used in these systems includes voice response units (VRUs), fax servers, speech recognition and voice recognition hardware, and Intelligent Peripherals that are deployed by telephone companies.

Today’s businesses need to leverage the power of these diverse, multi-user Computer Telephony systems to improve productivity, give users more access to information, and provide communications options and services to both customers and employees.

Business customers can use the telephone to automatically receive information about a product through a fax machine.
Employees can access computer-managed voice, fax, and even data (text messages and other information) through telephones, computers, or both, to effectively connect offsite workers to the office and to expand relationships with the external community.
The Computer Telephony industry is opening up to offer the power of sophisticated telephony systems to businesses, large and small, in the same way that the PC industry opened up in the 1980s. In a little over a decade, the Computer Telephony industry has grown to encompass many diverse applications and technologies. For 1995 alone, analysts estimate the revenue from multi-user Computer Telephony applications, development toolkits, and services and technologies to be $4 billion worldwide!

Understanding CT Technologies

Interactive Data Concepts, Inc. (IDC) is committed to provide products that enable customers to achieve success in their chosen markets by developing and providing quality software and hardware solutions for automated call processing applications. IDC products combine a number of technologies to enable users to store, retrieve, and manipulate computer-based information over a telephone network.

Voice Processing

Voice is the fundamental technology at the core of most Computer Telephony systems. It encompasses both the processing and the manipulation of audio signals in a Computer Telephony system. Tasks include filtering, analyzing, recording, digitizing, compressing, storing, expanding, and replaying signals.

Telephone Network Interfaces and Tone Processing

Network interface technology enables computer telephony systems to communicate electrically with specific telephone networks. Calls arriving from telephone networks can be carried on a variety of lines, from analog loop start and DID (DDI) lines to digital T-1, E-1, and primary rate Integrated Services Digital Network (ISDN) lines. Network interfaces also interpret signaling coming across the telephone line, provide data buffering, and include surge protection circuitry. Dialogic provides network interface boards for computers that work with all the popular telephone networks around the globe. Tone processing includes the capability to receive, recognize, and generate specific telephone and network tones. This capability allows an application to place a call and monitor its progress. Tones that are processed include: busy tones, special information tones (SIT), no answer, connection, ringing, no ringing, dial tones, fax machine tones, modem tones, and R2 MF tones.

Facsimile (Fax)

Facsimile (Fax) technology lets you transmit copies of documents (paper and electronic) and images over telephone lines to another location. To transmit and receive electronic faxes, PC-based systems use fax boards. This computer-based fax technology can improve productivity by allowing documents to be sent through a broadcast fax to a large number of people in a very short period of time. In addition, people can retrieve any number of documents on demand (FaxBack) that are residing on a fax server.

Automatic Speech Recognition (ASR)

Automatic speech recognition (ASR) technology (also known as voice recognition) reliably recognizes certain human speech, such as discrete numbers and short commands, or continuous strings of numbers, like a credit card number. Speaker-independent ASR can recognize a limited group of words (usually numbers and short commands) from any caller. Speaker-dependent ASR can identify a large vocabulary of commands from a specific speaker. Speaker-dependent ASR is popular in password-controlled systems and hands-free work environments.

Text-to-Speech (TTS)

Text-to-speech (TTS) technology generates synthetic speech from text stored in computer files. TTS provides a spoken interface to frequently updated information and information stored in extensive computer databases. TTS is an economical way of giving customers telephone access to information that would be too expensive or impractical to record using voice technology.


Switching technology handles the routing, transfer, and connection of more than two parties in a call. These capabilities, which were once the province of private branch exchanges (PBXs) and proprietary switches, are now available on expansion boards that can be easily incorporated into PC-based Computer Telephony systems.

Understanding CT Solutions

Customers use Dialogic/GammaLink building block components to develop open systems products that are sold in all of the major Computer Telephony markets. These markets can be grouped into four major sections: Information Access and Processing, Messaging, Connectivity, Central Office (CO)/Advanced Intelligent Network (AIN).

Information Access And Processing Applications

More and more businesses worldwide are expanding their corporate communication systems to automate employee access to information and the capability to process some of that information. For example, a customer may want to check on the balance of a loan, then get a fax report of the adjusted interest charges for early payment. Information access and processing applications can improve communication and increase customer service levels. These systems include audiotex, fax-on-demand (FOD), interactive voice response (IVR), interactive fax response (IFR), and simultaneous voice and data.

Audiotex (AudioText)

Audiotex provides prerecorded information to callers. Businesses can offer callers a single message or a choice of messages through touch-tone or automatic speech recognition (ASR).

Fax-on-Demand (FOD)

Fax is indispensable to the way business is done today. Businesses with dedicated fax-based systems or with fax as an enhancement to their existing communications systems can automatically deliver information on demand, to their customers. For example, customers can dial in and listen to a menu telling them which documents are available by fax. They can make a selection by speaking or by pressing a touch-tone digit, then enter the number of their fax machine to receive the document.

Interactive Voice Response (IVR)

Interactive Voice Response (IVR) allows customers to manipulate information in a computer database, such as retrieving an account balance and transferring funds from one account to another. These applications range from Audiotex and Pay-Per-Call information systems that deliver a single audio message or a selection of messages to transaction-based systems that allow callers to access accounts and update information on a LAN-based or host-based database. Audiotex entertainment lines are popular applications in emerging Computer Telephony markets.

Interactive Fax Response (IFR)

Interactive Fax Response (IFR) allows customers to automatically receive a fax in response to a transaction performed through either the telephone or a computer. For example, a customer may receive a printout of an account balance after having transferred funds.

Electronic Mail (Email) Reader

An electronic mail (email) reader resides on a media server that uses text-to-speech (TTS) technology. Email readers translate the ASCII text of an email message (stripping out unnecessary header information) into voice that can be retrieved by callers through any analog device, such as a telephone.

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