Private Branch Exchange Research Articles

Telephone application programming interface-based, speech enabled automatic telephone dialer using names

A speech enabled automatic name dialer dialing system for connection to a telephone system, includes a user computer with a computer-based address book program for retrieval of name-telephone number data for creation of speech enabling phoneme sets for auto dialing by speaking a name, and utilizing telephone application programming interface (TAPI), for use with a telephone systems having telephones with private branch exchanges. There is at least one user computer having a microphone and a speaker; a telephone application programming interface provider installed in the user computer; and at least one loaded address book program or equivalent name-telephone number data base contained in the user computer. The software for the user computer, which accesses the data base, creates the phonemes from names of data sets, receives voice inputs, matches the voice input phonemes to the data and signals to a router and PBX to initiate dialing.

Backward compatible wideband voice over narrowband low-resolution media

This paper proposes a scheme for transmitting or storing a wideband version of voice (up to 7 kHz) in a narrowband channel or medium (up to 3.4 kHz) with a low resolution data format. The scheme is fully backward compatible; a conventional receiver, without any decoding mechanism, can still access a narrowband version of the wideband voice. The proposed scheme can be applied where a high quality wideband voice is needed but the physical capacity is limited. Examples are voice-over-IP, digital private branch exchange, as well as storage and playback. An audio demonstration is given in the paper.

Unified messaging system with automatic language identification for text-to-speech conversion

A unified messaging system includes a voice gateway server coupled to an electronics mail system and a private branch exchange (PBX). The voice gateway server provides voice messaging services to a set of subscribers. Within the voice gateway server, a trigraph analyzer sequentially examines 3-character combinations within a text message; determines occurrence frequencies for the character combinations; compares the occurrence frequencies with reference occurrence statistics modeled from text samples written in particular languages; and generates a language identifier and a likelihood value for the text message. Based upon the language identifier, a message inquiry unit selects an appropriate text-to-speech engine for converting the text message into computer-generated speech that is played to a subscriber.

Competing after radical technological change: the significance of product line management strategy

AbstractResearch on firm performance after the introduction of a radical technological change has primarily concerned itself with differences between incumbents and entrants. This paper explores other factors that may influence firm performance over the longer term after a radical change—specifically, those related to product line management strategy. Following a radical change, a period of incremental technological change typically creates the opportunity for rapid development of new products. In such settings, strategies to manage multiple products, including families of related products that can be derived from a common platform, may be expected to impact competitive performance, especially over the longer term. The data for the study are from the telecommunications switching sector, specifically the private branch exchange (PBX) industry. Fifty‐six firms and over 240 new products were analyzed over 22 years. This study shows that incumbent–entrant‐based explanations of firm performance are incomplete. In particular, the results demonstrate that product line strategy explains significant additional variation in firm performance. The paper tests hypotheses linking both overall product line strategy and product platform strategy to firm performance. It finds that overall product introduction rates and product longevity can be linked to performance. It also shows that decomposing overall strategy into product platform strategy—rates of platform and derivative introduction, and platform longevity—can further increase explanatory power. In total, the results indicate that strategic prescriptions in the literature that emphasize development speed alone are oversimplified. They also suggest that differences in how relationships among products derived from a common platform are managed can contribute to competitive advantage and demand complex trade‐offs. Copyright © 2003 John Wiley & Sons, Ltd.

Digital business telephones-project laser

In enhancing its 8400-series digital telephones used with the DEFINITY® private branch exchange (PBX), the Audio Display Terminals team decided to address simultaneously the challenges of reducing product design time and costs, and increasing manufacturing throughput and product reliability. In response to market management, the team — consisting of market management, research and development (R&D), and manufacturing in Lucent Technologies' Business Communications Systems (BCS) Business Unit — also needed to ensure that DEFINITY system customers could easily interchange the redesigned products with the earlier telephone sets, stipulating that the look and operation of the new products remain the same as before. The result was an initiative known as Project Laser, which implemented specific product improvements based on customer input, competitors' features, and three fundamental technology strategies. The design of the product line was optimized to support the new manufacturing process in the company's Shreveport, Louisiana, factory, and component integration was refined to provide future application flexibility. This paper discusses the Project Laser initiative, a breakthrough undertaking for BCS.

IP exchange systems-Redefining distributed communications in the enterprise

The IP Exchange systems, which include IP ExchangeComm† and IP ExchangeLink†, are Internet protocol (IP) private branch exchanges (PBXs) designed and developed by Lucent Technologies. They are implemented using an advanced distributed computing architecture that leverages open computing and communications standards to create a scalable, reliable switching and feature service platform. This paper introduces the IP Exchange systems and presents their technical approach, their innovative architecture, and the benefits of that architecture.

Integrating Internet telephony services

Cost savings and the ease of developing and adding new services have motivated great interest in Internet telephony, which integrates services provided by the Internet with the public switched telephone network (PSTN). Internet telephony relies on several protocols, including the real-time transport protocol (RTP) for multimedia data transport and the session initiation protocol (SIP) or H.323 for establishing and controlling sessions. SIP can integrate with other Internet services, such as email, the Web, voice mail, instant messaging, conference calling, and multimedia collaboration. We have implemented a SIP-based software suite called the Columbia Internet extensible multimedia architecture (Cinema), which we installed and integrated with the existing private branch exchange (PBX) infrastructure in the computer science department at Columbia University. The Cinema environment provides interoperability with the PSTN, programmable Internet telephony services, and IP-based voice mail. It also integrates Web access and e-mail for unified messaging and supports multiparty multimedia conferencing. The setup lets us extend our PBX capacity and will eventually let us replace it while keeping our existing phone numbers. It also provides an environment in which we can easily add new services and features, including interoperation with existing multimedia tools, e-mail access from standard. telephones, network appliance control, and instant messaging support.

Implementation and performance evaluation for mobility management of a wireless PBX network

As wireless technology advances, wireless products are integrated with enterprise networking to offer cordless terminal mobility. Most corporations have deployed wireless PBXs at the departmental level. However, the mobility management mechanism that integrates these facilities at the corporation level may not be available. This paper describes a mobility management mechanism for an enterprise wireless telephone network. We show how, to modify the call model of the private branch exchange (PBX) to accommodate mobility management for an enterprise network. Our design was implemented on a commercial PBX product called Jupiter. An analytical model is proposed to evaluate the performance of the implemented system. Our study shows that with a large number of WPBXs and long Internet message delays, the misrouting probability can be limited to within 1%. This performance result is considered satisfactory.

Field Measurements of Electromagnetic Interference in Hearing Aids

This investigation was a preliminary field study to determine the acoustic and perceptual characteristics of hearing aid distortion generated by digital wireless telephones, the usability of the telephones under field conditions, and the extent of bystander interference under field conditions. A two-channel analog-to-digital converter was used to monitor voltages generated by an acoustic (real-ear) and electromagnetic probe. Digital recordings of interference and speech plus interference were made on a laptop computer. Fifty-three hearing aid wearers listened to interference and speech plus interference through personal communication service 1900 and time division multiple access digital wireless telephones and rated them in terms of annoyance experienced and usability of the wireless telephone. Ratings of annoyance were also done for the bystander condition. Approximately 80 percent of the sample rated the telephones as unusable; on the other hand, 70 to 90 percent experienced no annoying interference from telephones being used by another person seated nearby (bystander condition).

IP Telephony Solutions for the Customer Premises

Recent developments in IP telephony equipment have made it possible to provide a fully converged communications solution. This paper specifically concentrates on the customer-premises-based IP telephony solutions for the business market and in particular it looks at the next generation in IP-based telephones and private branch exchanges (PBXs). This also leads to the importance both of the network infrastructure, including local and wide-area networks, and of providing end-to-end quality of service to support voice as a real-time service. Suppliers are striving to develop the systems that will exploit the new converged world while at the same time deliver the reliability and functionality that customers demand. It is currently very much an early adopter market for these IP telephony solutions and experience drawn from delivering trials to external customers as well as the internal pilot work is used to provide a practical snapshots of today's solutions.

LIFE CYCLE ASSESSMENT OF A TELECOMMUNICATIONS EXCHANGE

This paper describes a comparative life cycle assessment (LCA) of a new Business Communication 10 (BC 10) and an old Business Communication 8 (BC 8) model of the private branch exchange Modular Digital 110 (MD 110), designed and sold by Ericsson Enterprise AB (EE) and produced by Flextronics, in this case for the European Union (EU) market. LCA is a technique for assessing the environmental aspects and potential impact associated with a product's whole life cycle from the "cradle to grave". The study meets the requirements of the standards International Organisation for Standardisation (ISO) 14040:1997 English (E), ISO 14041:1998 E and the draft standards ISO/Draft International Standard (DIS) 14042 and ISO/DIS 14043 and was critically reviewed by Henrik Wenzel, Instituttet for ProduktUdvikling (The Institute for Product Development, IPU) in Denmark. The modelling of the system includes manufacturing (hardware and EE's organisation), use stage (electricity consumption), end-of-life (recycling processes) and transports. Electronic devices are modelled in depth (16 groups of components) and data from over 40 suppliers have been collected. EE's organisation (development, marketing & sales, supply, installation, service and maintenance) is modelled for the use of offices and business travelling. The following main conclusions of the project are based on results for potential contributions to the environmental impact categories acidification, global warming and eutrophication, which were chosen to be the most relevant. The environmental impact improvements of the new model compared to the old are approximately 10%, and the uncertainty of the results is judged to be smaller than the difference between the systems.The use stage and the manufacturing stage give the largest impacts, both for the new and the old model. In the manufacturing stage, the hardware production clearly dominates. EE's organisation is secondly most important and hardware transport is least important. This is due to more environmental load from service and business travelling in the organisation than environmental load arising from the distribution of the product. The results predominantly reflect energy use, whereas toxicological aspects could not be reliably assessed due to lack of data and reliable methods and needs separate attention. The technology improvements shown for BC 10 compared to BC 8 only describe design improvements made by EE, and do not take into account potential technology production improvements made by component suppliers.

PBX based mobility manager for wireless local loop

SUMMARY In a typical wireless local loop (WLL) system, a user can only access the wireless services at xed locations. This paper proposes a private branch exchange (PBX) based mobility manager for WLL, which allows users to receive wireless service at any locations within the WLL service area. We show how the mobility manager can be implemented in a PBX environment where the base stations are connected to the PBX using standard line or trunk interfaces. The proposed mobility manager can be tailored to connect wireless system such as DECT or PACS. Copyright ( 2000 John Wiley & Sons, Ltd.

Feature-oriented engineering of PBX software for adaptability and reuseability

Incorporating a high level of adaptability and reusability into software is one challenge that all software engineers face. PBX (Private Branch Exchange) is one such system that requires a high level of adaptability and reusability because of rapidly expanding service features, ever changing communication technology, continuously evolving standards and diverse communication laws and standards in different countries. The software engineering community has made various efforts to address the problem of enhancing software adaptability and reusability. As a result, many programming concepts, such as information hiding, encapsulation, object orientation, abstract data type and modularization, have been developed. Although adequate application of these principles requires the domain or program family perspective, most methods, so far, have been oriented toward developing a single application. FORM (Feature-Oriented Reuse Method), the domain-based software reuse method applied in this paper, concentrates on analyzing and modeling commonalities and differences in applications of a given domain and using the analysis results to develop domain-oriented architectures and software components. The model that captures commonalities and differences is called the ‘feature model’ and it is used for both the engineering of reusable domain artifacts and the development of actual application software with reusable artifacts. We found that FORM facilitates analysis of variability, as well as commonality, of software before the start of engineering and implementation. With this understanding, adaptability and reusability can be built into software. Also, feature modeling has been found to be an effective method for identifying objects. Copyright © 1999 John Wiley & Sons, Ltd.

BEYOND INCUMBENTS AND ENTRANTS: AN EMPIRICAL EXPLORATION OF PRODUCT LINE MANAGEMENT STRATEGY AFTER RADICAL TECHNOLOGICAL CHANGE.

Research on firm performance after the introduction of a radical technological change has primarily concerned itself with differences between incumbents and entrants. This paper explores other factors that may influence firm performance over the longer term after a radical change -- specifically, those related to product line development strategy. Following a radical change, a period of incremental technological change typically creates the opportunity for rapid development of new products. In such settings, strategies to manage multiple products, including families of products that may be derived from a common platform, may be expected to impact competitive performance. The data for the study are from the telecommunications switching sector, specifically the private branch exchange (PBX) industry. 56 firms and over 240 new products were analyzed over 22 years. For the literature on competition after radical technological change, this study shows that incumbent-entrant based explanations of firm performance are incomplete. Specifically, the results demonstrate that various dimensions of product line strategy explain significant additional variation in firm performance.

True number portability and advanced call screening in a SIP-based IP telephony system

Custom local area signaling service features offered in the PSTN have certain limitations due to the closed nature of PSTN network signaling. The adoption of telephony over IP (IP telephony) will enable a new paradigm of services and features that are not possible to implement in today's PSTN. This is especially the case for services that make use of personal, trusted information, which can be provided by a user's personal digital assistant. We demonstrate how personal information can be coupled with an IP telephony service to provide user-customized call handling by the network. In particular, we describe a demonstration architecture that includes Ethernet-attached phones running SIP, with an interface to synchronize with PDAs that supply personal information. The proposed architecture is quite flexible; it can support enhanced versions of the current PSTN and private branch exchange services, in addition to many new features and services. We describe true number portability and advanced call screening as examples of new services in a hybrid PSTN/IP telephony environment.

Performance modeling of wireless PBX systems

This paper studies the effects of cell residence times on wireless private branch exchange (WPBX) systems. In a WPBX, several base stations are connected to a PBX, and the PBX is connected to the Public Switched Telephone Network. It is important to determine the external line capacity and the radio channel capacities of a WPBX to optimize its system performance. Our previous study utilized an analytic model to study WPBX without user mobility. This paper proposes both the analytic and the simulation models to investigate the performance for WPBX with user mobility. Specifically, we study the effects of handoff and the variance of the cell residence times on resource planning. Based on the workload to the WPBX, our study provides several guidelines to determine the capacities for the PBX and the base stations.

Resource planning for wireless PBX systems

The wireless private branch exchange (PBX)system offers wireless telephone access in an officeenvironment. In a WPBX, several base stations areconnected to the PBX, and the PBX is connected to thepublic switched telephone network (PSTN). Since onlya small number of telephones are expected to be busy atthe same time, the capacity (number of the externallines) between the PBX and the PSTN is typically smaller than the sum of the capacities (radiochannels) of the individual base stations. It isimportant to determine the capacity of the WPBX tooptimize the performance of the system. This paperproposes an analytic model and a simulation model forWPBX resource planning. Based on the workload to theWPBX, our study provides the guidelines to determine thecapacities of the PBX and the base stations.

FORM: A feature-oriented reuse method with domain-specific reference architectures

Systematic discovery and exploitation of commonality across related software systems is a fundamental technical requirement for achieving successful software reuse. By examining a class/family of related systems and the commonality underlying those systems, it is possible to obtain a set of reference models, i.e., software architectures and components needed for implementing applications in the class. FORM (FeaturedOriented Reuse Method) supports development of such reusable architectures and components (through a process called the “domain engineering”) and development of applications using the domain artifacts produced from the domain engineering. FORM starts with an analysis of commonality among applications in a particular domain in terms of services, operating environments, domain technologies, and implementation techniques. The model constructed during the analysis is called a “feature” model, and it captures commonality as an AND/OR graph, where AND nodes indicate mandatory features and OR nodes indicate alternative features selectable for different applications. Then, this model is used to define parameterized reference architectures and appropriate reusable components instantiatable during application development. Architectures are defined from three different viewpoints (subsystem, process, and module) and have intimate association with the features. The subsystem architecture is used to package service features and allocate them to different computers in a distributed environment. Each subsystem is further decomposed into processes considering the operating environment features. Modules are defined based on the features on domain technology and implementation techniques. These architecture models that represent an architecture at different levels of abstraction are derived from the feature hierarchy captured in the feature model. Modules serve as basis for creating reusable components, and their specification defines how they are integrated into the application (e.g., asdis integration of predcoded component, instantiation of parameterized templates, and fillingdin skeletal codes). Our experiences have shown that for the electronic bulletin board and the private branch exchange (PBX) domains, “features” make up for a common domain language and the main communication medium among application users and developers. Thus, the feature model well represents a “decision space” of software development, and is a good starting point for identifying candidate reusable components.

Analysis of composite walls and their effects on short-path propagation modeling

For short-propagation paths, correctly representing reflections of electromagnetic energy from surfaces is critical for accurate signal-level predictions. In this paper, the method of homogenization is used to determine the effective material properties of composite materials commonly used in construction. The reflection coefficients for block walls and other types of materials calculated with these homogenized effective material properties are presented. The importance of accurately representing the reflections for signal-level prediction models is also investigated. It is shown that a 5-10-dB error in received signal strength (RSS) can occur if the composite walls are not handled appropriately. Such accurate predictions of signal propagation over a short distance is applicable to microcellular personal communications services deployments in urban canyons as well as indoor wireless private branch exchanges and local-area networks.

Lessons from the design of a PC-based private branch exchange

We designed TigerSwitch, a digital private branch exchange (PBX) implemented on an IBM PC-compatible platform, as an experiment in embedded system design. A telephone switching system is an interesting example of embedded system co-design because it combines a rich functionality with deadlines ranging from seconds to tenths of a millisecond. This paper uses design decisions from TigerSwitch to illustrate the difficulties faced in the partitioning and allocation of a system specification into an architecture: the critical performance paths may not be obvious from the initial specification, and it is often difficult to obtain the performance data required to allocate functions in the architecture.