Object-Oriented Telephony System

Portions of this patent application contain materials that are subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever.

1. Field of the Invention

This invention relates to telephony systems and more particularly to a system for interfacing application elements with telephony elements.

2. Description of the Prior Art

Current telephony systems are fairly rudimentary, having changed very little from the basic principles of early telephony. Early systems often utilized switchboard operators for making connections between calling and called parties. By using computer technology, the need for such operators has been reduced to providing assistance in only special circumstances.

Other technological advances have turned telephony systems into an information transfer network or data highway. Facsimile is one of many examples which use the telephony system as an information transfer network. Perhaps the heaviest use of telephony systems comes from simple voice phone calls between calling and called parties. This interaction however, takes least advantage of telephony system capabilities.

Moreover, a typical user only has the most basic of equipment, which is designed for mere real-time voice transmission. The telephony system, however, is capable of transfering other infomation in addition to voice, and is also capable of providing a variety of information transfers which more fully utilize the available bandwidth and network capabilities of the telephony system.

The typical PBX is a classic example of a technology whose power has outstripped the available means of delivery. The average user makes use of only a tiny fraction of the full capability of most modern phone systems. The standard telephone handset is a human-interface bottleneck. At best, it is characterized by rows of buttons which must be labeled because there is no conventional mapping between position and function. Unfortunately, the labels give no clue as to the sequence in which the buttons must be pressed to accomplish a given operation. The presence of multi-function buttons (Transfer/3-Way Conference) adds further confusion to the picture.

While telephone companies have used computer technology to take advantage of, and to advance the potential of, the telephony system, the individual user has not been able to exploit the potential to the same extent. The closest an individual user comes to exploiting the potential of a telephony system is when a phone answering machine is used, and perhaps accessed remotely.

The telephone is really just a primitive terminal. A connection to another terminal is established by lifting the receiver to signal that network services are desired and then inputting a sequence of numbers which identify the terminal connection. The connection is terminated by hanging up. These simple operations provide convenience in creating a simple connection, but other aspects of the phone system require users to keep track of a variety of details.

For example, phone numbers are often memorized or kept manually in a handwritten notebook which must be carried around at all times. Address books, index cards, and massive lists printed on cheap paper and bound in unwieldy tomes are also frequently used. But storage is only part of the problem. Before they can be used, the numbers must be accessed--retrieved from memory, looked up in the card file or directory. And since numbers change over time, they must also be periodically updated. Storing numbers electronically in personal or on-line databases can mitigate the problems of retrieval and maintenance to some extent, but after it is located the number must still be manually transferred to the telephone set.

A telephone set also provides a less than ideal user interface in the case of operations which are more complex than establishing a simple one-to-one connection. In the case of a conference call, for example, the average user needs to check the reference manual to determine what sequence of keys to use: is it "*7" or "*8"? One alternative is to provide a special telephone set equipped with a row or two of extra buttons--the telephony equivalent of function keys on a computer keyboard, except that the labels on telephone buttons are typically a little longer: "TRNSF" for call transfer rather than "F6".

Therefore, there is a need to untap the potential of the present telephony system, especially the information transfer and network capabilities of the system.

It is an object of the present invention to provide improved access to telephony elements.

It is another object of the present invention to apply computer technology to telephony systems.

It is yet another object of the present invention to provide an interface between telephony system elements and application elements.

It is also an object of the present invention to make the boundary between the telephony world and generic sound world appear smooth and seamless.

The above objects are realized by providing elements which flexibly interface with various telephony system elements. These interface elements typically do not replace the telephone system elements, but rather provide a transparent way of interfacing with particular telephone system elements. The interfacing elements are designed to interface with particular elements of the telephony system, whether the telephony system elements of the telephony system are hardware elements, or merely protocols. For example, an interface element could provide a simple interface for receiving a call, and notifying an application element that a call is pending.

The interface elements provide a flexible and convenient way in which a programmer developing an application program involving telephony can utilize telephony system features without concerning themselves with the details of how the feature is accessed for a particular telephony system. The interface elements are also useful to hardware designers of telephony equipment.

Computer-based telephony has the potential to eliminate the limitations of the phone set while at the same time providing tight integration of telephone-based communications with applications running on the desktop. It is an essential part of the system foundation required to enable remote, real-time collaboration.

The present invention allows applications to access whatever internal telephone hardware is available on a target machine and provides generic dialing functionality via a modem or other external hardware device.

An object-oriented operating system is an essential element of computer-based telephony applications in a preferred embodiment.

Other objects and advantages of the present invention will become apparent from the following detailed description when viewed with the accompanying drawings.

FIG. 1 shows a representative system in accordance with a preferred embodiment;

FIG. 2 shows a typical hookup of a handset to a wall jack in accordance with a preferred embodiment;

FIG. 3 shows a handset hooked up to multiple lines and multiple jacks in accordance with a preferred embodiment;

FIG. 4 shows a computer-based telephony system utilizing a modem in accordance with a preferred embodiment;

FIG. 5 shows a computer-based telephony system having a computer interposed between the handset and jack in accordance with a preferred embodiment;

FIG. 6 shows hardware in accordance with a preferred embodiment;

FIG. 7 shows the instantiation of a TTelephoneLineHandle object in accordance with a preferred embodiment;

FIG. 8 shows the functional characteristics of TTelephoneLineHandle. in accordance with a preferred embodiment;

FIG. 9 shows the instantiation of TTelephoneCallHandle in accordance with a preferred embodiment;

FIG. 10 shows the functional characteristics of TTelephoneCatlHandle in accordance with a preferred embodiment;

FIG. 11 shows an application creating an interest in accordance with a preferred embodiment;

FIG. 12 shows a telephony system sending information in accordance with a preferred embodiment;

FIG. 13 shows the playback of a sound file in accordance with a preferred embodiment;

FIG. 14 shows an application interacting with TTelephoneLineHandle to perform various telephony transactions in accordance with a preferred embodiment;

FIG. 15 shows configuration data in accordance with a preferred embodiment;

FIG. 16 shows the functions of TTelephoneLineHandle in accordance with a preferred embodiment;

FIG. 17 shows the functions of TTeIephoneLineFeatureControl in accordance with a preferred embodiment;

FIG. 18 shows the functions of TTeIephoneHandsetHandle in accordance with a preferred embodiment;

FIG. 19 shows TInterest subclasses in accordance with a preferred embodiment;

FIG. 20 shows TNotification subclasses in accordance with a preferred embodiment;

FIG. 21 shows the functional characteristics of TTelephoneLine in accordance with a preferred embodiment;

FIG. 22 shows a development cycle for a designer of telephony equipment in accordance with a preferred embodiment;

FIG. 23 shows the functional characteristics of TTelephoneLine in accordance with a preferred embodiment;

FIG. 24 shows the functional characteristics of TTelephoneLineHandset in accordance with a preferred embodiment;

FIG. 25 shows the functional aspects of TTelephoneLineFeature in accordance with a preferred embodiment;

The detailed embodiments of the present invention are disclosed herein. it should be understood, however, that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, the details disclosed herein are not to be interpreted as limiting, but merely as the basis for the claims and as a basis for teaching one skilled in the art how to make and/or use the invention.

As used herein, "telephony system" includes all aspects of telephonic communication.

Historically, telephone networks standards have been established on a country-by-country basis. In many cases they have been subject to considerable variation, creating a localization nightmare, especially in Europe. Because of emerging digital standards such as ISDN (Integrated Services Digital Network) and the formation of the European Community in 1992, this situation will likely be ameliorated in the near future. In the United States, where incentives to move rapidly to ISDN are not as strong, we will very likely have to contend with two parallel networks, one analog and one digital, for some time to come.

In the analog domain, computer control of telephony functions is typically performed via a modem. (Note that the modem need not necessarily be a piece of external hardware. RISC and chip-based Digital Signal Processing technology make possible the implementation of fully functional internal software modems.) A widespread de facto standard for computer-to-modem communication is the so-called "AT" command set originally defined by Hayes, Inc.

In the digital domain the ISDN standard has been developed by a multinational working group of the CCITT (International Telegraph and Telephone Consultative Committee). The ISDN network layer protocols for setting up and tearing down connections are defined in CCITT Recommendation Q.931. (ISDN also includes specifications for physical and data link layers, as well as for a higher-level management entity.)

Between the telephone network and the telephone handset lies a switch of some sort which links a specific extension to the network. In the commercial market, this switch is most likely a PBX (Private Branch exchange). Aside from providing simple connections via the network, switches typically provide a variety of so-called supplementary services, such as holding, transferring, and conferencing. The protocols for accessing these services not only vary significantly, but have historically been proprietary to each switch manufacturer. While the ISDN network layer specification in Q.931 does address supplementary features, considerable latitude remains in the choice of features and in the actual sequence of messages used to implement a given feature.

Depending on the type of network and on the interface between computer and telephone network, it may be possible to record audio data off the phone line for storage and playback on the computer. In the case of analog data, a pathway to Analog to Digital Conversion services would have to be provided, and the data could then be represented using whatever internal standards are valid for a given design center. In the case of digital data, the matter of external standards arises. CCITT has defined several data format standards compatible with the ISDN B-Channel transfer rate of 64,000 bits per second. There are 2 standards for uncompressed voice signals which take advantage of the full available bandwidth. Both of these are based on log-companded PCM (Pulse Code Modulation). In the first case, which is the primary format for North America, log-companding is provided by the It-Law function, in the second, which has been adopted primarily in Europe, the A-Law function is used. Each assumes an 8 KHz sample rate and allocates 8 bits per sample, providing an effective signal bandwidth of 3.5 KHz.

A number of standards for audio compression have been adopted by CCITT on the one hand and by the digital cellular industry on the other.

In a preferred embodiment, the invention is implemented in the C++ programming language using object-oriented programming techniques. As will be understood by those skilled in the art, Object-Oriented Programming (OOP) objects are software entities comprising data structures and operations on the data. Together, these elements enable objects to model virtually any real-world entity in terms of its characteristics, represented by its data elements, and its behavior, represented by its data manipulation functions. In this way, objects can model concrete things like people and computers, and they can model abstract concepts like numbers or geometrical concepts. The benefits of object technology arise out of three basic principles: encapsulation, polymorphism and inheritance.

Objects hide, or encapsulate, the internal structure of their data and the algorithms by which their functions work. Instead of exposing these implementation details, objects present interfaces that represent their abstractions cleanly with no extraneous information. Polymorphism takes encapsulation a step further. The idea is many shapes, one interface. A software component can make a request of another component without knowing exactly what that component is. The component that receives the request interprets it and figures out according to its variables and data, how to execute the request. The third principle is inheritance, which allows developers to reuse pre-existing design and code. This capability allows developers to avoid creating software from scratch. Rather, through inheritance, developers derive subclasses that inherit behaviors, which the developer then customizes to meet their particular needs.

A prior art approach is to layer objects and class libraries in a procedural environment. Many application frameworks on the market take this design approach. In this design, there are one or more object layers on top of a monolithic operating system. While this approach utilizes all the principles of encapsulation, polymorphism, and inheritance in the object layer, and is a substantial improvement over procedural programming techniques, there are limitations to this approach. These difficulties arise from the fact that while it is easy for a developer to reuse their own objects, it is difficult to use objects from other systems and the developer still needs to reach into the lower non-object layers with procedural Operating System (OS) calls.

Another aspect of object-oriented programming is a framework approach to application development. One of the most rational definitions of frameworks come from Ralph E. Johnson of the University of Illinois and Vincent F. Russo of Purdue. In their 1991 paper, Reusing Object-Oriented Designs, University of Illinois tech report UIUCDCS91-1696 they offer the following definition: "An abstract class is a design of a set of objects that collaborate to carry out a set of responsibilities. Thus, a framework is a set of object classes that collaborate to execute defined sets of computing responsibilities." From a programming standpoint, frameworks are essentially groups of interconnected object classes that provide a pre-fabricated structure of a working application. For example, a user interface framework might provide the support and "default" behavior of drawing windows, scrollbars, menus, etc. Since frameworks are based on object technology, this behavior can be inherited and overridden to allow developers to extend the framework and create customized solutions in a particular area of expertise. This is a major advantage over traditional programming since the programmer is not changing the original code, but rather extending the software. In addition, developers are not blindly working through layers of code because the framework provides architectural guidance and modeling but at the same time frees them to then supply the specific actions unique to the problem domain.

From a business perspective, frameworks can be viewed as a way to encapsulate or embody expertise in a particular knowledge area. Corporate development organizations, Independent Software Vendors (ISV)s and systems integrators have acquired expertise in particular areas, such as manufacturing, accounting, or currency transactions as in our example earlier. This expertise is embodied in their code. Frameworks allow organizations to capture and package the common characteristics of that expertise by embodying it in the organization's code. First, this allows developers to create or extend an application that utilizes the expertise, thus the problem gets solved once and the business rules and design are enforced and used consistently. Also, frameworks and the embodied expertise behind the frameworks have a strategic asset implication for those organizations who have acquired expertise in vertical markets such as manufacturing, accounting, or bio-technology would have a distribution mechanism for packaging, reselling, and deploying their expertise, and furthering the progress and dissemination of technology.

Historically, frameworks have only recently emerged as a mainstream concept on personal computing platforms. This migration has been assisted by the availability of object-oriented languages, such as C++. Traditionally, C++ was found mostly on UNIX systems and researcher's workstations, rather than on Personal Computers in commercial settings. It is languages such as C++ and other object-oriented languages, such as Smalltalk and others, that enabled a number of university and research projects to produce the precursors to today's commercial frameworks and class libraries. Some examples of these are InterViews from Stanford University, the Andrew toolkit from Carnegie-Mellon University and University of Zurich's ET++ framework.

There are many kinds of frameworks depending on what level of the system you are concerned with and what kind of problem you are trying to solve. The types of frameworks range from application frameworks that assist in developing the user interface, to lower level frameworks that provide basic system software services such as communications, printing, file systems support, graphics, etc. Commercial examples of application frameworks are MacApp (Apple), Bedrock (Symantec), OWL (Borland), NeXTStep App Kit (NEXT), and Smalltalk-80 MVC (ParcPlace) to name a few.

Programming with frameworks requires a new way of thinking for developers accustomed to other kinds of systems. In fact, it is not like "programming" at all in the traditional sense. In old-style operating systems such as DOS or UNIX, the developer's own program provides all of the structure. The operating system provides services through system calls--the developer's program makes the calls when it needs the service and control returns when the service has been provided. The program structure is based on the flow-of-control, which is embodied in the code the developer writes.

When frameworks are used, this is reversed. The developer is no longer responsible for the flow-of-control. The developer must forego the tendency to understand programming tasks in term of flow of execution. Rather, the thinking must be in terms of the responsibilities of the objects, which must rely on the framework to determine when the tasks should execute. Routines written by the developer are activated by code the developer did not write and that the developer never even sees. This flip-flop in control flow can be a significant psychological barrier for developers experienced only in procedural programming. Once this is understood, however, framework programming requires much less work than other types of programming.

The invention is preferably practiced in the context of an operating system resident on a personal computer such as the IBM.RTM. PS/2 .RTM. or Apple.RTM. Macintosh.RTM. computer. A representative hardware environment is depicted in FIG. 1, which illustrates a typical hardware configuration of a computer in accordance with the subject invention having a central processing unit 100, such as a conventional microprocessor, and a number of other units interconnected via a system bus 132. The computer shown in FIG.1 includes a Read Only Memory (ROM) 104, a Random Access Memory (RAM) 106, an I/O adapter 112 for connecting peripheral devices such as disk units 108 and other I/O peripherals represented by 110 to the system bus 132, a user interface adapter 128 for connecting a keyboard 130, a mouse 126, a speaker 122, a microphone 124, and/or other user interface devices such as a touch screen device (not shown) to the bus, a communication adapter 116 for connecting the workstation to a data processing network represented by 114. A display adapter 120 for connecting the bus to a display device 118. The workstation has resident thereon an operating system such as the Apple System/7 .RTM. operating system.

Voice-oriented applications of computer-based telephony fall into 3 categories depending on their basic requirements:

1) Applications which rely on software control of telephony features without provisions for capturing or accessing the voice signal;

2) Applications which do need to record and play back voice data; and

3) Applications which assume simultaneous transmission of voice and non-voice data.

Over the years, a variety of devices have been devised to make the telephone more useful. Many of these involve computer-controlled telephony.

Applications of this genre directly address the issue of the advanced telephone system which is so complex that it is used to its full potential by less than 10% of its users. The basic problem with such systems has to do with the fact that the average telephone handset is a device with a very low interface bandwidth. Each new feature added to the phone systems results in another button on the handset (or--shades of MS-DOS--another special sequence of numbers to memorize: "*3" to transfer, "*5" to forward).

Software control of such functions from the desktop, combined with a well-designed graphical user interface, will help end-users to bypass the arcane idiosyncrasies of their local PBX and enable them to start benefiting from the technological improvements that telephone equipment manufacturers have managed to achieve since the days of Alexander Graham Bell. A good example of this concept is Northern Telecom's Meridian TeleCenter, which runs on current Macintoshes, but of course operates only with Northern Telecom's own PBX's.

In it's simplest form, computer-controlled telemarketing tools simply permit automatic dialing from a database of telephone numbers. More sophisticated variants dial out on multiple lines and detect when a human being has answered on the other end of the connection, or present detailed customer information on the screen for each dialed party.

The idea here is to place Voice Mail on the desktop in order to bring it up to the level of functionality we have come to expect from text mail systems. The typical Voice Mail system today is a centralized service which is parallel to and completely isolated from all other forms of electronic communication.

Even when they are available, such features as group addressing and on-line directories are difficult to use via a standard push-button phone set and must be set up and maintained separately from electronic mail databases even though they contain duplicate information. Calling in to check one's voice mailbox is just one more unnecessary detour in the flow of information through office and home. The Voice Mail systems of this decade are analogous to the centralized computer systems of the Seventies.

Some of the improvements to existing telephone services which are just now becoming widely available will be greatly enhanced by the migration of voice messaging to the desktop. For example, the ability for the receiving party to examine the phone number from which an incoming call was placed (so-called Calling Party Identification) will, among other things, permit the user to set up personalized greeting messages. For example, if I am expecting an important call from my brother, John, and I know I may not be in when he calls, I can record a message to be played when my computer answers any call originating from one of the phone numbers listed for him in my electronic address book.

The presence of a computer on the receiving end of a call also increases the potential for manipulating messages once they have been recorded. Any editing of audio data is obviously out of the question if one's only terminal is a push-button handset. With the increasing use of digital formats for transmission of voice data (as with ISDN) it is extremely wasteful not to provide a means for capturing the audio signal as it streams by.

To access your office computer system from home, all you need is a phone line, a modem and another computer. So what if you're at the airport and you realize you forgot to bring the address of the customer site you are going to visit? What if you arrive at your destination to find that the airline has lost your modem along with the rest of your luggage? What if you can't afford to buy a second computer? Then you need the ability to dial up your office system from a standard phone and access the information stored on your hard disk by asking the computer to read it to you. You'll also need Text-to-Speech Synthesis software on your office machine and a way to control the desktop using DTMF (dual-tone multi-frequency) keys or voice commands (i.e. Automatic Speech Recognition).

This term covers a broad range of applications which permit remote callers to listen to selections from a collection of prerecorded messages. These applications may be solely dedicated to information delivery (e.g. the IRS's Teletax service), or they may combine informational interactions with transaction processing (e.g. an order-entry service for a mail-order catalog or a bank-by-phone service which permits depositors to check account balances, transfer funds, and make loan payments).

Traditionally, putting together even a straightforward information delivery system has required a specialized team of programmers and systems integrators. At least one third party providing such services has developed a graphically-oriented tool on the Macintosh for generating a set of control files which are then uploaded to a stand-alone Voice Response system

Voice Bulletin Board Service

This is a voice-mediated version of the familiar electronic BBS. It is actually a hybrid of Voice Mail and Interactive Voice Response. Callers browse through various categories of voice messages left by other callers, then record their own messages in response.

The role that telephony services play in collaboration depends, of course, on the kind of collaboration we are talking about. Plain vanilla Voice Mail might be involved in sequential, asynchronous collaboration (e.g. reviewer receives copy of document, reads it privately, and responds with a voice message). Simultaneous, asynchronous collaboration involves placing a call to an author of a document (automatically extracting the phone number from a "business card" object attached to the document) so that a reviewer can deliver comments in person while the author is displaying a separate copy of the document. A third type of collaboration is simultaneous, real-time collaboration a la CHER, in which a document is simultaneously updated by author(s) and reviewer(s). The degree to which collaboration of this last type enhances the interaction of team members will no doubt vary in inverse proportion with their physical proximity to one another. It is in the case of remote collaboration among geographically dispersed work-groups that telephony comes into play. The basic idea would to maintain a standard voice connection while simultaneously transmitting and receiving document updates over a data connection. Such an interaction could be carried out over two standard phone lines or over a single ISDN connection.

Another intriguing application of simultaneous voice and data transmission involves the use of an inexpensive video camera along with a video digitizer card to transform a standard ISDN connection into a poor man's video phone. In other words, a voice connection can be enhanced by the periodic bi-directional transmission of captured video frames showing the callers' faces and/or objects held up to the video camera. Even when the frame-rate is extremely low, the end result can be quite interesting.

The present invention has been designed to empower application writers to blaze new trails in all three areas.

The present invention is designed to enable the development of computer-based telephony applications, and allow telephony designers to exploit these newly developed applications. The telephone is in essence a primitive terminal used to establish a connection to another terminal by lifting the receiver to signal that network services are desired. A sequence of numbers identifying the terminal you wish to connect with is then input. The connection is broken by hanging up. The present invention supports computer-based telephony by providing a high-level interface to voice-oriented telephone functions. These functions include the "lowest common denominator" of the capabilities in typical telephony configurations. The invention is intended to insulate application-level code from differences in the equipment through which these functions are accessed. At the same time, the invention provides a flexible framework which can be easily extended to include new features or to accommodate the peculiarities of various combinations of telephone sets, local hardware and software platforms, network types, and switch signaling protocols.

When such a flexible framework for interfacing is provided, numerous application program writers will develop software for exploiting the usefulness of such an interface. In turn, telephony system designers will desire to exploit the new application elements, and will therefore also need interface elements to work with. Therefore, two types of objects will be useful to discuss: objects for application writers on the one hand, and objects for developers of extensions to the basic interface on the other. In general, objects of interest to application developers will also be of interest to telephony system developers. Each category will be discussed below. It should be kept in mind, however, that the headings below are for purposes of discussion only, and are not considered to be limiting in any way.

A telephony system is comprised of many elements which would be useful to interface with. In general, there are two categories of these elements. The first category involves the physical equipment which is used tin implementing a telephony system, while the second involves the transactions which are processed by the telephony system. Objects for each category will be discussed, and examples will be provided outlining possible types of interfacing elements.

From the point of view of the application writer, the present invention facilitates the implementation of simple and intuitive user interfaces for computer-based telephony applications. Hardware-independence of the objects will allow an application to run regardless of the phone system attached to the computer or the telephony features currently available to the end-user. A standard protocol allows an application to determine at launch time which of the features it "knows about" are active and which are inactive.

FIG. 2 shows the real-world telephony object most familiar to the end user: the single-line telephone handset 200 which plugs into a wall jack 204 to connect to a telephone line 202. The fact that there is an enormous "netscape" of wire, fiber, switches and central offices behind the wall jack does not enter into the consciousness of the average user. What is important is that a specific line 202 is now accessible via a specific handset 200. The correspondence between handsets and lines, however, need not be one-to-one.

A single phone line may be split into several extensions, each with its own handset (not shown) or, as illustrated by FIG. 3, a single handset 300 may provide sequential access to several lines 302, each connected to separate jacks 304. The former case is typical of residential installations. The multiline handset, on the other hand, might be used by a small business or by an administrative assistant supporting 3 executives. Typically, the end-user selects a line by pushing a labeled button somewhere on the handset 300.

FIGS. 2 and 3 are not labeled as prior art because handset 200 could be implemented to include the features of the present invention.

FIG. 4 represents a possible system for implementing computer-based telephony in accordance with the present invention. In the actual equipment configuration required for computer-based telephony, the telephone line 404 connects not to the handset 400 but to a computer 412 via the medium of an external device, such as a modem 408. Line 410 connects the computer 412 to modem 408, and line 404 connects modem 408 to jack 406. The handset 400, which is not even necessary for many applications, also connects to the external device 408 or telephone interface, and can usually be used to initiate or terminate connections independently of the computer 412. The computer may or may not be able to control and/or query the handset.

The computer 412 may be similar to that shown in FIG. 1, comprising a personal computer or even a workstation. Computer 412 may include a keyboard 414, display 416, and floppy drive 418.

FIG. 5 demonstrates a variation of the system of FIG. 4, showing a computer 508 which has a telephone interface for connecting handset 500 to jack 506 via lines 502 and 504, which can be built-in or card based. Computer 508, like that shown in FIG. 4, includes a keyboard 512, display 512, and floppy drive 514. Computer 508 is capable of responding to both handset 500 and signals coming over the telephone lines via line 502. Computer 508 is also capable of passing signals between handset 400 and jack 506 without modification.

The above discussion outlines some specific hardware which could be used to implement the present invention. It should be kept in mind, however, that such hardware is merely illustrative, and that the present invention could be implemented on a variety of systems and devices connected to the telephone network. FIG. 6 demonstrates a device embodying at least some of the principles of the present invention. Device 600 utilizes objects for interfacing with various elements of the telephony system 604 to which it is connected via line 602. Device 600 may or may not be connected to one or more devices 606.

It should also be noted that device 600 may advantageously be connected at points in the system other than to a jack. That is, the object-oriented device may be connected out in the network, interfacing with elements of the telephony system.

The system the present invention is implemented on should be capable of multitasking or multiprocessing. This would provide optimum performance of applications and use of system resources via the objects.

The applications running on the devices connected to the telephone system utilize specially designed interface elements to interact with the elements of the telephony system. It should be noted that the terminology "applications running" is meant to include not only software programs which are running on a computer, but also hardware which may be performing particular applications. These interface elements standardize the methods used for passing information from and to various of the telephony system elements. The interface elements are advantageously implemented using objects in a preferred embodiment.

FIG. 7 is a flow chart, beginning at step 700, demonstrating the instantiation of multiple TTelephoneLineHandles. As shown by steps 702 and 704, the present invention views the telephone line as a system resource which can be shared among voice-oriented applications, as long as it has not been previously reserved for data communications. Such applications actually access telephony services through the surrogate class TTelephoneLineHandle (step 706). In order to permit the user to maintain operation of an answering machine application, for example, in the background while launching repeated instances of, say, an auto-dial application in the foreground, multiple TTelephoneLineHandles may be instantiated for the same line and distributed across team boundaries (steps 706 and 708). The process of instantiation ends at step 710 when no further TTelephoneLineHandles are necessary, but may be repeated each time an instance of TTelephoneLineHandle is needed.

FIG. 8 shows a possible flow of operations characteristic of the functions carried out by TTelephoneLineHandle. In addition to permitting the state of the telephone line to be modified (steps 802 and 804) and queried (steps 806 and 808), TTelephoneLineHandIe provides member functions for creating a standard TMicrophone (steps 810 and 812) or TSpeaker (steps 814 and 816) object representing the line's audio input or output capability, if any. The functional flow of TTelephoneLineHandle is delineated by steps 800 and 818.

Note that from the point of view of the voice application, it is immaterial whether the "real" telephone line is connected to the computer via the physical modem device illustrated in FIG. 4, or via some type of internal interface, as in FIG. 4. All the application "sees" under either configuration is a TTelephoneLineHandle.

TTelephoneHandsetHandle represents the physical telephone device as opposed to the telephone line. The standard TTelephoneHandsetHandle class has member functions for reporting its hookswitch state and for creating a standard TMicrophone or TSpeaker object representing the handset's audio input or output capability, if any. If such capability is present, the handset will typically operate in two modes, one in which audio is routed directly to and from the physical telephone line, bypassing the computer altogether, and a second in which audio is routed to and from the computer, leaving the physical line out of the loop. Before a handset can be used as a local speaker or microphone, however, it must be explicitly "disconnected" from the physical line. Note that the speaker and microphone created by a TTeIephoneHandsetHandle are completely independent of those created by a TTelephoneLineHandle. Playing audio data to the handset's speaker causes sound to come out of the handset. Playing data to the line's speaker causes sound to be sent over the telephone network.

Subclasses may include physical handsets with buttons, displays, or external speakers and microphones with associated gain controls. There is, of course, a "lower" common denominator: a telephone device whose switch status cannot be monitored. In this case, a TTetephoneHandsetHandle object would not be terribly useful. Even when switch status is available, the standard version of TTelephoneHandsetHandle is completely optional for the typical computer-based telephony application.

In addition to the hardware-type entities associated with use of the telephone network (described above), there are less tangible objects. For example, the connection itself, or, as an end user might think of it, the telephone call could be considered an intangible. A call has an existence and state independent of the telephone line. To make a call a user must first "find" a telephone line. ("Where can I find a telephone? I need to make a call.") To receive a call, a user needs to know which line it is coming in on. ("Mr. Smith, you have a call on line 1.") A line is either on-hook or off-hook, while a call passes through a variety of states during its lifetime. In many cases, a single line can support multiple simultaneous calls where the user has placed one call on hold in order to place a second, outgoing call. Alternatively, a user may add a call to an existing connection to produce a three-way conference call.

In the real world, information about the progress of a call is communicated back to the user via the audio channel: a continuous tone indicates that the call can be dialed, an interrupted tone indicates that the destination line is busy, a "ringing" tone indicates that the destination phone is ringing, etc. In computer-based telephony interfaces these same signals may be obtained, as well as subtler details about a call's state, in the form of alphanumeric status indications.

As shown in FIG. 9, between steps 900 and 910, applications initiate and terminate telephone connections by asking (step 902) an instance of TTelephoneLineHandle to create a TTelephoneCallHandle (step 904).

FIG. 10 shows a functional flow for TTelephoneCallHandle. As shown between steps 1000 and 1010, TTelephoneCallHandle provides access methods for determining the state of the connection (steps 1002 and 1004) as well as for returning the telephone number of the remote endpoint (step 1006 and 1008).

Since TTelephoneLineHandle only permits calls to be placed, answered, and hung up, a family of classes has been provided to facilitate access to the more popular supplementary voice features. In addition to creating calls, a Line Handle can create individual feature control objects for whatever set of advanced features happens to be available. Examples of such features may include the following feature set: Hold, Transfer, Conference, Drop, and Forward. Note that the availability of features depends not only on what the telephony hardware platform is potentially capable of providing, but also on which features the user has actually subscribed for.

FIG. 11 is a flow diagram illustrating how an application 1100 sets up to receive certain notifications regarding telephone systems. Clients 1100 wishing to receive any of the notifications discussed below must register interest in them using the standard Notification framework. TInterests 1104 for telephony notifications must be created by calling one of the "create interest" member functions provided by TTelephoneLineHandle and TTelephoneHandsetHandle 1102.

FIG. 12 illustrates telephony equipment 1200 sending out information via objects which can be used to manage telephony transactions. Information regarding the state of lines, calls, and features is propagated outward from the underlying telephony hardware by means of three telephony-oriented subclasses of TNotification. TTelephoneStatusNotification transports at 1202 an instance of one of three telephony-specific subclasses of Tlnterest: TTelephonelnterest, TTelephoneCalllnterest or TTelephoneFeaturelnterest. Status updates themselves are represented by TToken constants. TTelephoneRingNotification propagates information at 1204 about incoming calls. TTelephoneDigitsNotification at 1206 permits clients to receive DTMF digits generated by the remote endpoint.

TPhoneNumber, TPhoneEndpoint, and the other classes can be used to represent telephone numbers.

The TSpeaker and TMicrophone objects returned by TTelephoneLineHandle and TTelephonehandset are subclasses of the speaker and microphone classes. One caveat: data format standards for digital telephony may differ from location to location. Voice data coming in from an ISDN line, for example, will be log-companded rather than linear and digitized at 8 KHz rather than 22 KHz. To address this potential incompatibility, the present invention contemplates format conversion classes. For example, format conversion classes may include: T8KMuLawTo22KConverter, T8KALawTo22KConverter, T22KTo8KMuLawConverter, and T22KTo8KALawConverter.

FIG. 13 provides an example of playing back a sound file using instances of format conversion objects. To play back a sound file originally recorded directly from a North American ISDN line, for example, one would connect the output port of the file 1300 to the input port of an instance of T8KMuLawTo22KConverter 1302. One would then connect the output port of the converter to the input port of an instance of TSpeaker 1304 and call the file3 s Play member function. Type negotiation is used by audio ports to select a common data format.

This section describes in detail the classes and member functions of the present invention which were introduced above.

As shown in FIG. 14, to make use of available telephony resources, at 1400 an application instantiates a TTelephoneLineHandle as described above. A telephone connection can then be established by calling the line's CreateAndPIaceCall, represented by 1402, or CreateAndAnswerCall, represented by 1404, methods, both of which return a call handle.

To acquire control of an ongoing connection, the line's CreateCallList method would be used, represented by 1406. Connections initiated in any of these three ways are terminated by calling HangUp on the call handle, represented by 1408.

This class represents the configuration of a specific telephone line. As shown by FIG. 15, TTelephoneLineConfigurationData 1500 identifies the directory numbers associated with the line's local endpoint (1502) and specifies via type negotiation which telephone features are currently available on the line (1504).

TTelephoneLineHandle has been previously discussed with respect to FIGS. 7 and 8. FIG. 16 shows the functions associated with TTelephoneLineHandle, which is the standard surrogate for a telephone line. It permits selection of a specific line via a telephone line configuration data object (1600) and provides member functions for initiating telephone call connections (1602), determining the hook status of the line (1604), matching telephone feature types via type negotiation (1606), and creating audio objects for the line (1608). It also generates TInterest subclasses to be used by the notification framework (1610) for registering interest in telephony events associated with the line. TTelephoneLineHandle is multi-thread safe, but has not been designed for sharing across team boundaries.

This is a lightweight surrogate for a telephone connection. It permits clients to determine the remote number participating in the connection and the current status of the call. TTelephoneCallHandle has been discussed previously with respect to FIGS. 9 and 10. TTelephoneCallHandle is multi-thread safe, but has not been designed for sharing across team boundaries.

FIG. 17 shows the creation, at 1700, of TTetephoneLineFeatureControl by TTelephoneLineHandle in response to a client. TTelephoneLineHandles may or may not be capable of supporting arbitrary sets of features above and beyond the ability to make and break telephone connections. For example, a line handle may be able to place a call on hold, transfer a call, conference in a new call, or forward itself to a different line. Clients access features such as these by asking the line handle to create a subclass of TTelephoneLineFeatureControl. Feature control subclasses are specified by means of TTypeDescriptions based on the class names of the desired features. TTelephoneLineFeature-Control is multi-thread safe, but has not been designed for sharing across team boundaries.

Five standard feature control subclasses have been provided, corresponding to the "Big Four" supplementary features plus call forwarding.

This class represents the configuration of a specific telephone handset. It identifies the telephone line or lines to which the handset may be connected. This has been discussed with respect to FIG. 15.

FIG. 18 provides a functional representation of TTelephoneHandsetHandle, which is the standard surrogate for the physical telephone terminal equipment. It provides a mechanism for monitoring hook status (1800) and permits the creation of audio objects (1802, 1804) corresponding to the handset's internal speaker and microphone. It also generates TInterest subclasses to be used by the notification framework (1806) for registering interest in telephony events associated with the handset. As a physical device, a handset normally provides manual control for a specific telephone line so that lifting the handset causes some telephone line somewhere to go off hook. Before being used for audio I/O, the handset must be "Disconnected" from its line. It is also possible to connect a handset to one of a set of phone lines. TTelephoneHandsetHandle is multi-thread safe, but has not been designed for sharing across team boundaries.

FIG. 19 shows TInterest subclasses. The present invention makes use of three specialized TInterest subclasses to communicate status updates: TTelephoneInterest 1900, TTelephoneCallInterest 1908, and TTelephoneFeatureInterest 1912. TTeIephoneInterest 1900 permits clients to request notification of certain telephony events affecting a particular telephone line or handset. These events include changes in hook status 1902, ring indications from incoming calls 1904, and the arrival of remotely generated digit strings 1906. TTelephoneCallInterest 1908 permits clients to request notification of changes in the progress of a particular telephone connection 1910. TTelephoneFeatureInterest 1912 likewise permits clients to request notification of changes in the progress of a particular instance of a telephone feature 1914. Clients should create instances 1916 of the above classes by calling the appropriate member functions provided by TTelephoneLineHandle and TTelephoneHandsetHandle. None of them is multi-thread safe.

The following public static constants are defined for use with the Notification Framework:

FIG. 20 shows the functional relationships which result from TNotification subclasses. There are three telephony-oriented subclasses of TNotification. TTelephoneStatusNotification 2000 transports a status update 2002 and contains a TTelephoneInterest, a TTelephoneCallInterest, or a TTelephoneFeatureInterest (2004) in place of a plain TInterest. Status updates may be assigned to one of four categories, depending upon the progress of the operation with which they are associated: Success, Failure, In Progress, or Unknown. This permits applications to perform a preliminary classification of an incoming notification without explicitly examining its status field. TTelephoneRingNotification 2006 transports the phone number of an incoming call before it has been answered 2008. Finally, TTelephoneDigitsNotification 2010 transports raw DTMF digits from a remotely connected telephone's keypad 2012. Clients will typically obtain instances 2014 of these classes via the Notification Framework 2016 rather than by creating instances of their own. These classes are not multi-thread safe.

The following public static constant TToken references are defined for telephone status updates within the scope of TTelephoneStatusNotification::

Line status constants

kOnHook--Line or handset is on hook.

kOffHook--Line or handset is off hook.

Call status constants

kCallIdle--Call is inactive. The default state.

kIncompleteCallInfo--Call placement is in progress but more information is needed.

kCallReorder--Call placement could not proceed. There was an error in the number.

kCallCannotComplete--Call placement could not be completed.

kReadyToDial--Dial tone is present.

kFastBusy--Dial tone timed out.

kDialingComplete--Dialout completed successfully.

kRingbackDetected--A ringback indication was received. The destination phone is ringing.

kBusyDetected--A busy indication was received. The destination phone number is busy.

kNoAnswer--The destination phone number was not answered.

kCallActive--The call has been successfully connected.

kCallOnHold--The call has been put on hold.

kCallTerminationDetected--The network or the connected party has terminated the call.

Feature control constants

kActivateInProgress--The feature activation request was acknowledged.

kActivateComplete--The feature is now activated.

kCannotActivate--The feature could not be activated.

kDeactivateInProgress--The feature deactivation request was acknowledged.

kDeactivateComplete--The feature is now deactivated.

kCannotDeactivate--The feature could not be deactivated.

kErrorState--An unidentified error occurred.

ETelephoneStatusClassification is an enemy defined within the scope of

TTelephoneStatusNotification: to denote the generic classification of a status notification so that clients can respond appropriately without examining the state value. Defined values are:

kSuccess--Operation Completed Successfully

kFailure--Operation Prevented from Being Completed

kinProgress--Operation Is Proceeding Normally

kUnknown--Progress of Operation is Unknown for this State

Data format conversion is accomplished via converters such as T8KMuLawTo22KConverter, T8KALawTo22K-Converter, T22KTo8KMuLawConverter, and T22KTo8KALawConverter. These classes inherit from MAudio and add no new interface protocol of their own.

In addition to the objects discussed above, telephony systems developers will need to have further objects to work with when developing new telephony equipment. For example, third party developers such as AT&T who may wish to add support for proprietary phone equipment and/or to extend the present invention to accommodate advanced telecommunications capabilities. The present invention will make these efforts of third party developers as quick and painless as possible. The telephone architecture should anticipate the need for such extensions while maximizing potential reuse of the existing code associated with standard objects.

Telephony Developers need to concern themselves with three classes which were not described above in the applications section. The abstract Telephone Line class defines a standard interface to telephone network functions. It has a master-surrogate relationship vis-a-vis TTelephoneLineHandle and contains a built-in mechanism for communicating with its handles, which may exist in multiple teams. An interface for accessing common supplementary features beyond simple on/off hook and dialing functions is provided by TTelephoneFeature and its subclasses. Developers wishing to provide access to standard functionality on proprietary telephony hardware will need to produce subclasses of the line class and the predefined feature subclasses. Telephone Lines

FIG. 21 represents the abstract base class TTelephoneLine which provides a software model of the physical connection to the telephone network. With each phone line is associated (1) a hook state (on or off) 2100, (2) a TPhoneEndpoint containing a unique set of Directory Numbers 2102 and (3) a collection of its available telephony features 2104. In addition, a line manages a list of active handles 2116 to which it directs notification of status updates.

TTelephoneLine contains pure virtual member functions for going offhook, going on-hook, and dialing out digits. Implementations for each of these functions must be provided by the developer. In most cases, such implementation will require communication with an I/O Access Manager and/or a listener task specific to a given hardware/software environment.

If, for example, the physical telephone interface were resident on a nu-bus card running a particular Task A, the role of the device driver might be filled by a TaskACard object instantiated as a member field of the TTelephoneLine subclass. A call to the subclass's OffHook method would cause the line to send a message containing the appropriate command and data to the TaskACard. Responses would be routed back to the line via a listener task containing a TaskAListener. The line subclass would then create the appropriate TNotification subclasses and pass them down to associated TTelephoneLineHandles via the ReceiveUpdate method inherited from TTelephoneLine.

Two additional member functions which may be of interest to a developer are CreateSpeaker, and CreateMicrophone. These two functions have default implementations which simply return a NIL pointer. The request dispatcher, however, is set up to flatten non-NIL pointers for resurrection by the TTetephoneLineHandle on the other side. A preferred embodiment includes audio objects corresponding to the actual telephony hardware and appropriate calls to the sound server to instantlate these objects. Note that in many cases (e.g. a standard external modem connected over the serial port) it will not be possible to pass actual voice data in or out of the host computer and the default implementations will, unfortunately, have to be retained.

It is the responsibility of the TTelephoneLine subclass to ensure that the notification events expected by the line handle and call handle classes are generated in the proper sequence. Telephone Features

In order to provide advanced features beyond those required for setting up and tearing down connections, it is contemplated that the basic TTelephoneLine class support dispatching and processing of requests for advanced telephony features such as "hold", "drop", "transfer", "conference" and "forward", to name five of the more popular ones. The specific set of features available on a given telephone switch depends both upon the inherent capabilities of the switch, and upon the services the switch customer has chosen to subscribe for. Because of this and because of the fact that switch manufacturers come up with newer and fancier features each year, TTeIephoneLine operates on a heterogeneous set of features, polymorphically activating and deactivating them.

Continuing with FIG. 21, the subclasses of TTelephoneLineFeature are shown. TTelephoneLineFeature is the base class from which all features derive and which defines the activation/deactivation protocol. From TTelephoneLineFeature 2104 is derived a set of standard feature subclasses: TTelephoneHoldFeature 2106, TTelephoneDropFeature 2108, TTelephoneTransferFeature 2110, TTelephoneConferenceFeature 2112, and TTelephoneForwardFeature 2114. With each of these is associated a type description to be used by any subclass which preserves the feature's control protocol. Standard type descriptions for the five features listed above are provided by TTelephoneLineFeatureControl via static member functions.

A developer who wishes to provide implementations for the standard feature set must create subclasses of TTeIephoneHoldFeature 2106, TTelephoneDropFeature 2108, TTelephoneTransferFeature 2110, TTetephoneConferenceFeature 2112 and TTelephoneForwardFeature 2114, overriding the inherited pure virtual functions Activate and Deactivate so that useful work is performed.

FIG. 22 shows the procedures which are followed if there are advanced features for which no standard TTelephoneLineFeature subclass exists 2202. At 2204, if the feature is standard, it is used. If the feature is not standard, it is up to the developer to provide a type description at 2206 by overriding the pure virtual member function GetTypeDescription and to provide implementations of Activate and Deactivate 2208. The developer must also define a feature control subclass 2210 to present to line handles and must override CreateFeatureControl 2212 so that it returns an instance of the control.

The present invention employs two types of configuration information. Conversion from a displayable to a dialable number, for example, requires that the local area code be known, as well as the prefix for accessing long distance service. Information of this category may vary from location to location, but is common to all telephone lines installed at a given site. The local telephone number, on the other hand, and the features available to the extension associated with that number, are pieces of information which vary from line to line within the same site.

In a corporate setting, site-specific configuration information might be provided by a system administrator and included with the installation package distributed to individual users. Users would still have to specify the line-specific configuration. Non-corporate users would be responsible for providing both sets of information. The actual display and collection of configuration data may require that the developer produce either a special application or a data model capable of collecting input.

Configuration information is represented by TTelephoneLineConfigurationData, a lightweight configuration class which contains all site and line-specific configuration data required by a given TTelephoneLine. A similar relationship obtains between TTelephoneHandsetConfigurationData and TTelephoneHandset. These two classes are described in the preceding section.

If a developer's TTelephoneLine subclass is capable of capturing and reproducing actual voice signals, it is up to the telephony developer to provide the audio classes required to support this capability via the Sound Server. A developer interested in providing audio I/O from an ISDN card, for example, would write MAudio/TAudioProcessor pairs to represent the input and output capability of that hardware.

This section describes in detail the classes and member functions of the developer's tools introduced in the previous section. Developers who want to implement standard functions and features for a specific telephony environment will subclass TTelephoneLine as well as the standard TTelephoneLineFeature and TTelephoneLineFeatureControl subclasses. Developers who want to add new features and functions will need additional subclasses of TTelephoneLineFeature and TTelephoneLineFeatureControl. Developers who must support specialized terminal equipment will write subclasses of TTelephoneHandset and TTelephoneHandset Handle.

FIG. 23 shows the functional actions of TTelephoneLine 2300. This is the basic object representing a telephone line. It provides a low-level interface to simple telephone network functionality. Functions include: TakeOffHook 2302, PutOnHook 2304, DialNumber 2306, SendDigits 2308. The line creates TelephoneCallHandles 2310 to represent connections, obtains TTelephoneFeatureControls 2312 from its set of TTelephoneLineFeatures, and may also be capable of creating microphone and speaker audio objects 2314. A TTelephoneLine is associated with one or more surrogate objects called TTelephoneLineHandles. Handles relay requests to their master line, which, in turn, distributes telephone hook, ring, call, feature and digit notifications to the line handles. Advanced features such as hold, drop, transfer, conference are supported via subclasses of TTelephoneLineFeature. TTelephoneLine has been designed to be safely shared by handles belonging to different teams.

FIG. 24 shows the functional flows performed by TTelephoneHandset 2400. This is the basic object representing a physical telephone handset. It may also be capable of creating microphone and speaker audio objects 2402. A TTelephoneHandset 2400 is associated with one or more surrogate objects called TTelephoneHandsetHandles 2404. Handles relay requests 2406 to their master handset, which, in turn, distributes status updates 2408 to handles. TTelephoneHandset 2400 has been designed to be safely shared by handles belonging to different teams.

FIG. 25 shows the functions of TTelephoneLineFeature 2500. TTelephoneLineFeature is a base class which defines a standard set of advanced Telephone Line features. It defines a protocol for polymorphically Activating and Deactivating 2504 advanced telephony features 2510 and provides methods for determining their type 2506 and querying their status fields 2508. TTelephoneLineFeature is not multi-thread safe, but is accessed in a safe manner by the Line.

The constructor, destructor, and some other member functions of this class have already been described in the section on the interface for application writers. The following low-level control functions provided by TTeIephoneLineHandle may be useful when authoring a TTelephoneLineFeatureControl subclass.

The following is a similar list of functions for TTelephoneFeatureControl. These are used internally to implement the feature-specific protocol of the control. The pointer returned by GetLineHandle gives the control access to the public member functions of its associated line handle.

Interaction with the public telephone network itself is typically intermittent and relatively slow, thus imposing few, if any, strict performance constraints. Presence of audio data, on the other hand, brings in the standard set of real-time requirements that go along with analog-to-digital and digital-to-analog conversion hardware. Failure to keep up with the demands of such hardware introduces undesirable data discontinuities which not only degrade the intelligibility of speech data but can be extremely unpleasant (if not painful) to listen to. These real-time requirements, however, should not compromise the performance of non-real-time processes such as user interface widgets.

Specifically, recording or playing back one channel of audio does not provide any noticeable adverse effects upon such standard user operations as (a) selecting a menu item, (b) typing a character, (c) selecting a graphic object or (d) a range of text. This should be possible under each of the following scenarios:

1)8 KHz log-companded samples captured from telephone handset and recorded to disk

2)8 KHz log-companded samples captured from telephone network and recorded to disk

3)8 KHz log-companded samples retrieved from disk and played back to handset

4)8 KHz log-companded samples retrieved from disk and played back to network

5)8 KHz log-companded samples retrieved from disk and played back to system speaker

6)22 KHz linear samples retrieved from disk and played back to handset

7)22 KHz linear samples retrieved from disk and played back to network

Scenarios 5 through 7 require sample rate conversion with simultaneous companded-to-linear or linear-to-companded conversion.

In order for the present invention to operate with audio objects, the telephony objects support a variety of standards. For example, it is contemplated that both the .mu.-Law and the A-Law formats as well as providing for conversion to and from the standard audio format(s) is supported by target machines. By providing the capability of interacting with audio objects, the boundary between the telephony world and the generic sound world appears smooth and "seamless". It would be possible to instantiate via the Sound Server a standard microphone or speaker object which encapsulates the audio input or output capabilities of telephone lines and telephone handsets.

The above discussion provides a description of some exemplary objects which may be useful for interfacing with telephony equipment. Below provides examples using some of the objects discussed above.

The following provides an implementation of a call state machine utilizing some of the objects discussed above.

While the invention has been described in terms of a preferred embodiment in a specific system environment, those skilled in the art recognize that the invention can be practiced, with modification, in other and different hardware and software environments within the spirit and scope of the appended claims.