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• Learn about Computer Telephony
• Intel hardware and Development tools roadmap

Learn about Computer Telephony

Computer telephony is the technique of coordinating the actions of telephone and computer systems. This technology has existed in commercial form since the mid-1980s, but rapid technology development begin from the 1990s. This growth arises from defining international standards for interconnecting telephone and computer systems, such as the Computer-Supported Telephony Application (CSTA) call modeling and protocol standards from ECMA. Main operation systems software vendors (e.g. Microsoft and Novell) have specified its computer telephony application programming interface (API). As well as in other areas, computers can do business over the telephone at an increasing rate, which will return higher work force and rise financial yields.

Public (PSTN) and private telephone systems {PBX) provide real-time information paths between two or more parties. Traditionally, these information paths have taken the form of voice connections, originally through hardwired analog circuitry but later through an increasingly broad range of technologies such as radio transmission, digital signal encoding, and fiber. Over time, these transmission paths were also exploited for non-voice applications such as facsimile and data transmission.

At first, each non-voice application required a distinct set of dedicated "terminal equipment", the telephony term for any user device connected to the telephone network. Facsimile machines conversed only with other facsimile machines, computer devices sent data files only to other computer devices, and so forth. Big changes have begun in the 1990s when the general-purpose computer has emerged with special developed multi purposed equipment.

Computers can now send and receive every kind of information that passes through the telephone network: They can act as facsimile machines; they can interact with human speakers through voice synthesis and recognition; and of course they can send and receive data in many formats. General-purpose computer can serve as the interface point for the telephone network.

An import step was defining of the SCSA standard definition and its SCbus. SCSA allow to integrate easily computer telephony hardware and software produced by different vendors within one PC.

Typical computer telephony application must provide two tasks:

-Call establishing, call control and termination. These steps are similar to ordinary human telephone usage of phone or fax machine

-Information receiving and transmitting (voice, fax, binary). These operations provides data conversation (e.g. fax document) or act as on behalf of real human being. Keep phones conversation or listen to the caller.

All these tasks can be realized by the sophisticated computer telephony hardware. Leading hardware vendor is the Dialogic Corporation. Their products create highest industrial standard in the world of computer telephony technologies.

In simply terms, PC with modern telephony hardware is able to connect to the telephone line. With the Application Program Interface (API) and widespread program tools (e.g. C/C++, Pascal, Delphi, Visual Basic) is possible to write multi-lines application. Quantity of processed lines depends on selected hardware. Written application can be easily upgraded for higher channels (lines) quantity. Other solution would be usage of other standard, such as TAPI 2.0.

Development process described in previous paragraph may not be fast enough for some developers. Market offers long range of third party ActiveX components, which will shorten considerably application development.

When the time frame for development process and speedy application build up is crucial, customer may use special graphic and script editors. These editors are often very simply to use even for person without any experiences with code writing.

Computer Telephony nowadays doesn't insist on developer's telecommunication area technical knowledge. All instructions are explained in simply way with many links to industry resources. Computer Telephony applications emulate human being activity or function of real equipment (e.g. fax). API functions are equivalents to these activities: phone off hook, on hook, call #120, fax receive.

The CTI-PRO company offers its customers highly qualified technical support with consultations on telecommunication area all along business cooperation. Presales consultations, project planning, hardware and software development tools selections are free of charge. Priority after sales technical support and consultations will charged.

Earlier the proprietary telecommunications vendors did not offer open hardware solutions. The customer, who bought the product from chosen vendor, had no chance to use parts from other vendor. All daughter boards, accessories etc had to be bought from the same producer. Nowadays with an open standards and solutions telecommunication functions on different OS platform can be interfaced with other standards as LAN,WAN or Internet. This stage helps systems integrators to increase efficiency of information systems by elimination of useless repeating actions.

Computer Telephony software development tools makes possible development of full range applications from low density systems to complex high density LAN/WAN solutions for big corporations. Almost every product may be extended by the computer telephony functions. Detailed description and list of most popular CT applications are published on pages of CTI-PRO ltd. Other special application may be discussed with our employees who are willing to help you.

Intel hardware and Development tools roadmap

I. What operating system should we choose?

Everyone, who has decided to start the development of the computer telephony applications and selected the most wide-spread and the most complex hardware platform - the technology from the world leading company Intel, has to decide, what development tool will be used to develop with. The selection of the right operating system for the application development also influences this decision. Currently Intel company supports two operating systems - Microsoft Windows and various UNIX versions. Drivers and firmware designed for these operating systems are continuously being improved and support every newly released Intel voice boards, Windows NT versions are usually released a little sooner. The developer, who has selected one of these two operating systems, has the guarantee that he has selected the perspective platform with the assured quality technical support in the future. From the historical ground, there are also available drivers and firmware for the obsolete operating systems MS DOS/Microsoft Windows 3.X and OS/2. Intel finished support for these operating systems and they are designed only for the maintenance of formerly developed systems. It is strongly not recommend investing to the development of the new systems based on these platforms.

Because of the high popularity of the Microsoft Windows 95/98 operating systems in the desktop systems, Intel also offers the basic support for 2 and 4 port analog voice boards for these operating systems. However, it is only the basic support for the analog voice boards together with the support of the fax enhancements of VFX board, without the possibility of capitalization the other Intel platform's advanced features, including conferencing boards, Internet boards and network interface boards - E1, T1 and ISDN. Since the low multitasking quality inside Windows 95/98 operating system, there is not possible to control more than 16 channels. Despite of these limitations, this operating system should be successfully used for the cheap small-enterprise voice/fax solutions like automated attendants, voice mails or interactive voice response systems. It is possible to develop, with the help of the special cross-compatibility libraries, the applications that might work without any change either in Windows 95/98 or in Windows NT (or higher), because Win32 API of operating system Windows 95/98 is in the fact the subset of Win32 API of Windows NT, operating system. It implies the fact that the formerly developed computer telephony applications for Windows 95/98 operating systems should be converted to Windows NT with the minimum costs.

II. TAPI or not to-TAPI?

TAPI is the attempt for the standard based on the WOSA (Windows Open Services Architecture), designed by Microsoft company for the needs of Windows Telephony. The main idea was to create the exactly defined universal API for the different kinds of the hardware - starting from voice-modems, through voice boards from the different vendors and ending with the PBXs supporting the software control. However, this interface is available only for Windows 95/98/NT operating systems. It can be used neither in UNIX nor the obsolete operating systems OS/2 or MS DOS. The main advantage is the high level of the abstraction that frees the developer from the requirement of the detailed knowledge of the concrete hardware specifics. On the other side, just this high level of the abstraction is one of the arguments against the suggestion of the TAPI as the suitable application interface. Some feature cannot be used for their absence in the TAPI design, other because of nonexistence in TAPI drivers, so called TSP (TAPI Service Providers) - the vendor of the concrete hardware, simply, does not support these TAPI functions. And other TAPI functions do not work with the concrete hardware vice versa, because this hardware (typically various voice-modems) is not able to perform the affected functions.

Intel supports the basic TAPI functions for analog voice boards and each new drivers release brings the new support for a few another TAPI functions. The existence of TAPI support for Intel voice boards is very advantageous for the developers of the existing yet application working with common voice-modems, just based on TAPI. This enables them to adapt their existing systems to multiple port solutions (up to 16 channels on Windows 95/98 and up to 128 channels on Windows NT).

Regarding to the above, we can summarize our suggestion as follows. If there is not any special reason why to start to use just TAPI, then there is no reason to start the application development based on this interface. However, there is not any problem to use TAPI for the development of the very simple voice systems, while the developer is sure about the fact, the high-performance boards from Intel Corporation do not give him much more than common voice-modems. Actual limitation of the TAPI support for Intel boards in the rough corresponds to support of these boards' features in Windows 95/98, hence the use of TAPI for the voice application designed for this operating system does not bring any additional losses of the functionality.

III. What are the possibilities for the development of the computer telephony applications?

The application developer can choose from the several variants. He/she can decide to start his/her development based on C/C++ programming language, based on the special application programming language, based on the high-level ActiveX components inside his/her favorite visual development tool, or based on the special graphical application generators.

The basic Intel SDK for Windows is a part of the system drivers , that are downloadable from the Intel Website or to order he original CD-ROM from our company for the minimum fees. The similar SDKs are also available for the other operating systems supported by Intel. This SDK contains API functions, complete online documentation in *.pdf and *.hlp form, the large variety of the source codes as the samples of each Intel technology programming - starting with voice and fax features, through conferencing and routing functions, and ending with the functions for ISDN, E1 and T1 network interface control. Wide-range API functions are available only in the form of C headers and import libraries for C/C++ compilers: Microsoft Visual C++ 4.X (and higher) and Borland C++ 4.5 (and higher). It is very difficult to use this interface together with the other compilers like Borland Delphi, Borland C++ Builder, and Microsoft Visual Basic. It requires the complete changes of all headers and import libraries.

The direct use of Intel API should be suggested only to these companies, which can rely on the quality team of very experienced C/C++ programmers. Just the testing and learning of the software control of Intel hardware features and complex understanding of Intel system runtime library models ought to take also several months. It requires at least the partial knowledge of telephone traffic problematic, the initiating of the phone call, communication and control of PBX, hang-up detection etc. If the developer decides to start the direct development based on Intel SDK, he/she may not expect that without any previously built computer telephony applications, he/she would develop his/her own application within a few weeks. And moreover it would not be fail-safe and protected before the any errors and states occurring in the real telephone traffic and line signaling.

Although the direct development based on Intel SDK and C/C++ languages usually does not allow the quick deployment of computer telephony applications and requires the deep knowledge and experiences with C/C++ programming and telecommunication problematic, this disadvantage is replaced with the starting really zero-costs and the runtime licenses zero-costs per channels installed in the customers' systems.

IV. How to create computer telephony applications in Delphi?

Borland Delphi, Microsoft Visual Basic, Borland C++ Builder^TM, It is just an incomplete list of the today's so popular development tools for the rapid Windows application programming. Thanks to the wide-range of the third party additional components and the visual programming approach, it enables the high abstraction level of the work with the operating system's API functions as well as the many external devices. There exist more different ActiveX components from the hottest worldwide vendors for the high-level Intel hardware control. The solutions from American company Envox - ActiveX controls set called CT ADE The use these components by the any of the visual development tools listed above is the same as the work with the usage of the other components.

The purchase of these controls requires only one time development license fee. This license allows to develop the unlimited number of application, there is no additional runtime license fee for the really installed channels of the production applications. The features and the controlled hardware types organize these ActiveX controls to voice, fax, ISDN, conferencing, routing, Internet, conversion and support and others ones. The customer can buy only the development licenses for the controls that he/she really needs. He/she need not to buy the complete controls set, moreover, he/she can purchase only the required channel count licenses of each type. If he/she wants to develop and sell only the 8-channel application, he/she will have to buy only 8-channel development license of the required development ActiveX controls. This license policy allows to develop arbitrary number of different up to 8-channel applications, which installation do not require any additional fee to ActiveX control's vendor. These development licenses should be upgraded to the support of higher quantity of the channels.

Both vendors offer also TAPI versions of their ActiveX controls, so it is possible to develop the applications that works with the powerful Intel voice boards as well as the common voice modems.

The differences in the offered functions of these two products are not so big. CT ADE product has got the more consistent design and the better integration with all the development environments mentioned above.

The another important features include the support for the Intel DM/IPLink boards and HMP and Internet telephony solutions based on them.

Our suggestion for the selection of the ActiveX controls as the right development tool for computer telephony applications is as follows. If you have a good experiences in visual programming with any of the development environments listed above, there would not be any reason why not to select one of the ActiveX controls set discussed. The development time is incomparably more rapid than the direct Intel API programming and thanks the high-level of the abstraction there are not required so more detailed experiences in telecommunications. The most of the error states and the signaling is really simply processed and is very transparent for developer.

From the performance and stability point of view, we suggest these ActiveX controls sets for the computer telephony applications that manage up to 48 channels in the single PC. Although each vendor can declare the support for the rather higher count of channels, based on the practical results and test, we suggest only this number.

V. Is there any more rapid method to develop computer telephony applications?

The time to markets is in some situations the most dominant factor. Moreover, the expenses for the in-house well-educated C/C++, Borland Delphi or Visual Basic programmers may have the important influence. Not only for these cases, there exist the special graphical development tools. Their common feature is the visual plug-n-play application design approach. The help of the power blocks, mouse drags and clicks, develops the computer telephony applications. The application itself is in the fact the flowchart and there are directly visible the algorithms of the voice tasks. The licensing of these products is also the same, they are all, with slight differences, based on the runtime channels licenses. The development tool is usually the free-of-charge part of the purchased runtime licenses. The product differs from each other in the range of the supported Intel boards features and available operating systems versions.

The programming based on these development tools is easy, after the short experiencing, for almost any computer telephony novice, who has got the deeper experiences with the advanced users' programs like Microsoft Access.

Have a look on the some typical representatives of this group of the development tools. The one of the best products from this category is for example OmniVox from Apex Voice Communication. This tool enables the high-density channels application development (over 100) in the single computer running Windows or various UNIX versions. Especially, Digital UNIX for Digital Alpha Server 3000 allows the development of highly fault-tolerant industrial applications.

The similar product working only under Microsoft Windows operating system is ENVOX development tool. Among its unique characteristics it is one of the most intuitive development environments with the high level of the communication support. This product supports TCP/IP communications, e-mails, DHTML, serial port communication, RAS, as well as DDE communication. It is most suitable for the unified messaging system development. The another important feature of this product is also the support of Intel API interface GlobalCall, that allows virtually unlimited signaling support for T1, E1 or ISDN digital phone networks. Regarding the performance, there is not any problem to run the application based on CT-Studio on more than 64 channels in the single PC.

Finally for this development tools group we can summarize that almost everyone should find his/her right development tool inside this part. The costs for the runtime license of the production applications, developed with these graphical application generators is really balanced by the absolute speed-up of the developed application deployment to the market and the reducing of the computer telephony applications development costs.

VI. VOS - the tool which gurus use

The graphical application design need not be the fastest approach in all cases. Although, the visual application design is very fast and intuitive for the beginners, the classical programming direct source code writing approach can be better in some situations. The companies who want really professional focus on the design of the wide variety of the customers' computer telephony applications, especially the solutions for various audiotex services and conferences, need the development tool, that help them with the routine development of such applications. The most applications of this type are very simple and the visual programming should be persuaded as longer by some developers, because of the continual shifting of the hand between the mouse and the keyboard. However, they still require faster and simpler application design than the direct C/C++ programming of Intel API and the better performance and application stability than in the case of ActiveX components used with the standard visual development tools for Windows NT, such as Borland Delphi or Microsoft Visual Basic.

The answer for these demands brings actually the most powerful development tool for the computer telephony application development - VOS from Envox. VOS is the application programming language for the computer telephony applications programming, its syntax is similar to Fox Pro and Basic programming languages. It contains the set of executive functions and commands for the control of every Intel hardware features and their syntax is really intuitive and supports complete hardware features, hereat it is beyond comparable less complicated than the Intel API. The programming is so easy, that the Fox Pro or Basic programmer with the medium knowledge and experiences is able to create the complete audiotex system without any previous knowledge of the telecommunications. Just these capabilities together with the fact that VOS was historically the first development tool for the worldwide leading Intel hardware platform cause, that the most computer telephony systems are developed with this development tool.

The VOS source code is translated to P-code, that is interpreted by the powerful runtime engine supporting the preemptive multitasking well tuned just for the computer telephony applications needs. This runtime engine is written in the high-optimized C language code. Therefore the VOS applications has the same performance as the similar applications written in C language in the most powerful Intel API programming model. It is even true, that the same VOS application runs faster than the most of direct Intel API C/C++ implementations. Thanks this, VOS is suitable for the very small-enterprise solution as well as the high-density industrial solutions running in the single PC.

Each developer must purchase the one-time 8-port development license for the selected operating system. This license enables to develop applications running on the unlimited number of channels, however the debugging and the testing runtime are allowed only for 8 channels. Each production installation of the developed application requires the runtime licenses for the exact quantity of the used channels. The costs for these runtime licenses are really inconsiderable to the timesaving and the minimum requirements to the telecommunication knowledge.

You can purchase for the marginal additional charge the graphical shell of VOS for Windows, so called Flow Charter, that enables together with the classical non-visual application programming also the visual approach, that is the same as in the group of the graphical application generators described above. It should be advantage for the beginners who can use the graphical approach for the development of their applications or basic skeletons first and then together with gained better experiences they can switch to the classical programming approach.

The indispensable advantage of this development tool is the vendor's guarantee, that they will support every new hardware types and features from Intel, supported inside the selected operating system. The part of the development license is the lifetime free of charge technical support.

Everyone, who is thinking about the professional computer telephony application development and wants to support high density and fault tolerant solution and willing to be safe before the unexpected errors and situations in the real telecommunication traffic, should have really consider the selection of this development tool. Due its capabilities, it will not be the investment that should not have been paid off.

VII. Where to find the additional information?

The goal of this study is not to provide the full description of each alternative to the computer telephony application development. The main aim is to provide the brief compare of the each computer telephony application approach regarding the time and knowledge requirements, development speed and the approximate performance of the created application in the working environment. The basic information related to each development tools you can find at our Web pages.

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