Webster's dictionary defines telephony as "the science of communication by telephone." Unfortunately, this definition isn't very useful because these days "communication by telephone" covers a wide range of technologies--voice, fax, data, video, and pager communications all fall under the heading of telephony. This article broadens that definition by exploring telephony technology and its application in the Windows NT environment.
The Scope of Telephony
For years telephony services were handled by self-contained, proprietary hardware devices. These devices include telephones, videophones, pagers, dedicated fax machines, Private Branch eXchange (PBX) controllers, and more. During the mid-1980s, key telephony companies introduced telephony hardware and software solutions to commercial and personal computers. This means that UNIX systems--and now Windows NT Servers--can become PBX systems, and PCs can operate as phones, fax machines, and answering machines.
The integration of telephony and computers is called Computer Telephony Integration. CTI applications range from simple in-the-home phone solutions to full-scale enterprise-wide business solutions. For example, low-end CTI solutions enable you to:
- Use a computer as a single-line answering machine or voice mailbox
- Use a computer as a send/receive fax machine (In the world of CTI, the integration of computers and fax technology is called Computer-Based Fax, or CBF.)
- Use the microphone/speaker or speakerphone facilities on a multimedia computer as a phone system (If you're considering this application, be aware that it requires support for full-duplex audio operation--concurrent audio in and out--which is not normally available on most PCs.)
This level of CTI technology works well in home and small-business environments. Implementing CTI solutions for large corporate environments, however, requires a different level of technology. You need a highly reliable platform; you need better physical interfaces to the phone system; and you need more sophisticated CTI software to tie it all together. The payoff for this sophistication is a range of CTI solutions that enable you to:
- Use a computer system as either a multiline phone system or a multifunction PBX controller
- Implement an enterprise-wide voice-mail system in conjunction with--or as a replacement for--existing PBX equipment
- Set up on-demand audio information services that allow callers to retrieve prerecorded or computer-generated text-to-speech (TTS) information based on either touch-tone keys or actual voice input
- Set up on-demand fax services based on touch-tone keys or voice input that transmit information back to the caller
- Implement automatic, list-based dialing for telemarketing
- Deliver computer-based data related to a call (e.g., account balance, sales history, customer profile) to the desktop computer at the same time the call is switched to the desktop phone
- Set up one or more network-based fax servers that can route inbound and outbound fax transmissions to and from desktop systems on the network
- Implement on-screen, two-way voice/video conferencing
- Create a single, easy-to-use front end for managing all methods of communicating with an individual, such as voice, pager, or email
Implementing these kinds of solutions requires more than a garden-variety PC with a single fax/modem attachment.
CTI Platforms
Traditionally, enterprise-oriented CTI solutions have been based on stand-alone PC systems (DOS, Windows, or OS/2), NetWare servers, or UNIX platforms. These platforms offer a well-defined operating environment and standardized I/O buses to handle specialized telephony adapters. Recently, CTI vendors have embraced the Windows NT environment as the newest--and often preferred--platform for their CTI solutions because it offers several key benefits:
- NT offers proven stability and reliability. CTI applications tend to be mission-critical functions where reliability is a major consideration.
- Most telephony adapters support the ISA bus. Thus, Intel-based NT systems have access to a wide variety of telephony adapters because the software drivers for those adapters have been ported to the NT environment.
- NT provides an excellent development and runtime environment. It supports a broad range of development tools, and its graphical orientation can facilitate easy-to-understand user interfaces.
- The integrated network services in the NT environment offer flexible ways of distributing CTI functions and information across a network.
- The BackOffice suite of products provides a wealth of integration possibilities. CTI applications can be linked with Microsoft SQL Server, Mail Server, and Exchange Server. Many CTI vendors claim that telephony is another legitimate BackOffice function.
Telephony Adapters
At its core, a CTI application is a link into a telephone system. This link is a hardware interface adapter that connects the CTI platform to a public or private phone system. In other words, you plug this adapter into an ISA slot and connect it to your phone system. This component is critical because it establishes the limits of the application. For example, if you use a telephony adapter that supports only two direct-dial analog lines, then you can't have more than two active external calls.
Depending on the scale of a CTI solution, you may need additional telephony adapters or a single adapter that supports multiple functions. If you are implementing only a fax server or an Interactive Voice Response (IVR) solution, you can purchase a single interface adapter that provides both the main telephony link and the special function.
However, if you plan to implement a large-scale, multipurpose CTI server, such as voice mail, fax, and IVR, you'll need one or more telephony-link adapters and other interface boards to provide specialized services. For example, if you're going to provide fax services, you'll need dedicated fax adapters to handle your anticipated inbound/outbound load. Additional interface boards are available for TTS, IVR, and other functions.
The telephony-interface adapters plug into the host bus of the telephony platform (e.g., the ISA bus on an Intel-based NT system). In most cases, the adapters are interconnected over a second, specialized bus that operates independently of the main server bus. This enables the telephony interfaces to trade information quickly and efficiently, without draining the resources of the main bus.
You can achieve interoperability among different manufacturers' telephony adapters as long as they conform to the same standards or architectures.
Figure 1a and 1b show two examples CTI hardware configurations to illustrate the hardware concepts. (See the sidebar "CTI on the Network" for a description on how CTI applications integrate into computer networks.)
Telephony Software
Once the telephony hardware is in place, you need a layer of software to manage and control the various telephony operations and functions. The first layer of software includes the device drivers that integrate the adapters into the operating system (device drivers are provided by the adapter manufacturer). For example, the leading manufacturer of telephony adapters, Dialogic, has been busily porting its drivers to NT. Although the company hasn't ported all its drivers, it has moved a sufficient number to support most major CTI applications.
The software that actually implements the CTI application is normally provided by a different company. This software operates at a level above the device drivers and isolates you from the adapter-level components. When you purchase most CTI products, you see only the software interface and don't know--or probably care--whether the adapters came from Dialogic, Gammalink, Brooktrout, or someone else.
There are two categories of CTI products: toolkits that enable you to build custom CTI applications, and ready-to-run products. Often, Solution Providers and other Value-Added Resellers (VARs) use the toolkits as part of a larger business solution or to create CTI applications aimed at specific vertical markets. A CTI toolkit, such as Microsoft SQL Server, provides the tools to build an application but is not an application itself. The ready-to-run products, such as fax servers or voice mailboxes, can be general-purpose in nature. Or they can be built by a VAR or Solution Provider who uses a toolbox to address a specific business need (e.g., a CTI application that automates the placement of classified ads in a newspaper).
Various CTI software products and toolkits are available for the NT environment (see "Windows NT Telephony Buyer's Guide"). They run the gambit from simple voice-mail applications to sophisticated Help desk applications with built-in IVR and fax-back functions. Two examples of CTI products are OmniVox for Windows NT from Apex Voice Communications and Caléo Call Center from Caléo Software.
OmniVox for Windows NT is a telephony toolkit that allows you to quickly generate IVR, fax-back, and voice-mailbox applications. You produce an application by accessing a series of object-oriented icons that prompt for the desired operation (e.g., play a recording), the acceptable response (e.g., numbers 1 through 3 on a touch-tone pad), and the logic location where each response branches. The activity associated with each logic branch (e.g., record a message, send a fax, or gather more information) are then defined, creating a hierarchical logical structure.
In addition, OmniVox supports links to C and C++ routines, a scripting language, and access to external databases (e.g., SQL Server) via Open Database Connectivity (ODBC). These links enable OmniVox applications to connect to corporate data repositories and address other unique application needs, such as invoking validation routines.
The Caléo Call Center is a full-function automated call-management system that runs on NT and communicates with agent and supervisor modules running on Windows 95 systems (see Screen 1). The Caléo Call Center answers each call and determines where the call should be routed based on a series of questions and touch-tone key responses. Each call is routed to the appropriate queue and a second round of questions and responses gathers information, such as account and phone numbers. This information is logged in a database and sent to the agent computer when the call is transferred.
Calls that cannot be promptly serviced remain in a queue, where callers can access IVR and fax-back information without losing their places. Managers can view the status of queues and can move calls from one queue to another with on-screen drag-and-drop. Managers can monitor the activities of an agent system by listening in on the call or by viewing statistical information associated with agent activity.
The bottom line is that if you can dream up a telephony application, there's probably already a product to handle it. If not, you can always create your own with a toolkit or an Application Programming Interface (API). (See the sidebar "The Space Between".)
The Facts of Life
CTI products enable you to integrate telephony into your NT environment to create new applications for today's business situations. CTI solutions are powerful, but be forewarned: They involve a level of technology and complexity that you may not be accustomed to. (For some examples of telephony terms and technologies, see the sidebar, "A Quick Guide to Telephony Terms.")
CTI has clearly become a fact of life, and the use of CTI services makes up a large part of our daily business lives.
Given today's business climate, you shouldn't be asking, "Do I need CTI?" You should be asking, "Which CTI products will best benefit my business?"