- Overview
- Definition
- Market Dynamics
- Programmable Switching
- Architecture
- Host
- Application Program Interface
- Programmable Switch
- Features
- Openness
- Scalability
- Configurability
- Reliability
- Price Performance
- Standards Compliance
- Benefits
- Reduced Time To Market
- Service Differentiation
- Matching Feature Costs to Feature Revenues
- Flexible, Cost-effective Reliability
- Flexibility to Enhance the Application
- Return on, Investment
- Deployability
- Applications
- Wireline Infrastructure
- Wireless Infrastructure
- Enhanced Services
- The Future of Programmable Switching
- Glossary: Terms & Acronyms
Definition
Market Dynamics
The opening of telecommunication markets through deregulation, in concert with innovative technology, is creating both challenges and opportunities for developers, service providers and users of the network infrastructure and services. The availability of attractive new functionality is fueling market demand for connectivity, services and resources. The challenges in this environment for service providers, exchange carriers and other infrastructure players are:
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How to create and deploy new, differentiating services quickly and economically; |
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How to ensure that the telecommunications infrastructure remains open to change, accessible for growth,and easy to manage; and |
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How to safeguard and leverage their investments in applications and equipment. |
A new generation of cost-effective, flexible switching technology is making the implementation of new services technically feasible and economically compelling: open, scalable, high performance, programmable switching platforms. Through openness, the network infrastructure can accommodate and integrate a variety of external resources seamlessly, and can adapt to tomorrow's technologies. Through scalability, networks can be configured to meet initial market demand, and yet expand in both size and scope as the market grows. Through high performance, the telecommunications environment can sustain dynamic loads in real-time even as subscriber populations expand. And through programmability, a wide range of current and future requirements can be fulfilled flexibly and economically.
Programmable Switching
There are two defining characteristics of programmable switching:
- Call control, or switching, follows a logically sequence of events in a distinct call model, hence the term switching; and
- That call model is placed under the control of an application program, hence the term programmable.
Let's look at each in turn.
First, through programmable switching, a logically distinct, visible model is established for call control and processing, that is, the core switching function. Although modeling call flows in an identifiable manner was initially borne of the need to computerize the function in order to achieve high call rates, programmable switching provides an architecture to support that model. This approach contrasts with prior-generation technology such as private branch exchanges (PBX's) or central office switches that embedded switching and applications in a single fixed system. The call control model may be centralized and monolithic, or distributed and modular by varying degrees. With this approach, the model may be focused narrowly on traditional switching functionality, or it may extend to, for example, new services such as fax, video conferencing, voice processing, one-number or prepaid-services. An increasingly-used method of implementing the architecture of programmable switching is based on the open and distributed client/server computing model. Like the computer industry before it, the telecommunications industry today is discovering (1) the benefits of moving from large, proprietary solutions to open, scalable platforms; and (2) the importance of standards and interoperability between hardware platforms and software applications. Furthermore, the network infrastructure itself is making possible the concept of efficient clients and servers, whose system resources can be geographically distributed where and when they are needed. The figure below illustrates the parallels that exist between the computer and telecommunications industries:
Second, programmable switching opens up the call control/processing model so that developers can implement new and unique services. This capability enables service providers to differentiate their offerings in a highly competitive market. How open and accessible that programmability is varies greatly. In many cases, functions are implemented by the switch supplier, using proprietary software that is relatively inaccessible to others. In contrast, some switches can extend programmability to developers and service providers, by allowing them access to the switch software environment on one or more levels .Through the use of open strategies such as application programming interfaces, industry-standard interconnection devices, and high-level host-resident development tools, programmable switches can be tailored to implement unique services that meet individual market needs. As a result, carriers and network operators using an open switching platform can develop services much more rapidly and flexibly, and deploy them at a lower cost.
A Typical Programmable Switching Architecture
While there are alternative ways of designing a programmable switching environment, the implementation most consistent with an open distributed computing model consists of three major elements: hosts, switching systems, and messaging, as illustrated in the following diagram.
The Host
The host computer acts as the server for the client switch. From the standpoint of the switching model, the basic function of the host is to store and execute a varying amount of call control application software that manages the switch matrix and other services. Via a series of messages, or subroutines, known collectively as an application programming interface (API), the host drives the programmable switch. This architecture can thus provide an open API-based call processing platform that is distinct from the application. As a result of establishing this platform, developers can more easily create services to fulfill markets ranging from wireless infrastructure to prepaid services to enhanced services.
The openness of the interface between the host and the switching function is an important differentiator among programmable switches. Traditional switches are based upon a dedicated, preprogrammed controller which performs a specific set of duties, such as end-office switching, call center, private networks or wireless switching. Switches with a more open architecture, on the other hand, offer the service provider the ability to program the switching function. This ability gives them a tailorable system on which they can develop and deploy applications that meet their customers' needs and meet rigorous time-to-market demands. Consequently, service providers can have greater control and flexibility in delivering new services to their customers.
If the host is logically and physically separated from the switch, service providers also have the flexibility to select the host environment - such as hardware, database alternatives, operating system and programming language choices, reliability, performance, etc. -- that best meets their needs. Furthermore, open and programmable switching platforms have the flexibility to interoperate with a wide combination of internal resources and external environments, enabling the service provider to configure systems more economically and cost effectively to meet unique market needs.
Application Program Interface
The typical programmable switch interfaces to the host via messaging provided by an application programming interface (API). The larger, richer and more open the message set of the API, the greater the benefits.
An effective API delivers full control over individual switch operations and gives service providers a great deal of power and flexibility at both ends of the development spectrum. On one hand, service providers can implement applications quickly and easily to respond to market requirements. And on the other, they can build sophisticated, highly-customized applications to differentiate themselves from their competition. Some architectures take openness even further by supporting the ability to control individual resources in the switch (such as digital signal processors, network interface protocols and common channel signaling engines) through a programmable interface. High level programming tools with graphical user interfaces, as depicted in the following illustration, permit the control of individual events through modification and download of event tables. The more open the interface, the more flexibility results for the service provider.
Open APIs and high-level programming tools can give service providers a great degree of vendor independence. Through them, developers can implement custom software for their switching applications in a timely manner. Without open programming, service providers may have to rely on generic software provided with the platform that is neither tailored nor optimized to their individual needs. For revisions and releases, they must accept the manufacturer's schedule for delivery and the manufacturer's dictate for content. The result may be delays while a critical window of opportunity in their markets opens and closes.
Programmable Switch
The actual implementation of the switch or switch platform itself can vary substantially but it is generally composed of a matrix function, associated line interface cards, various common channel signaling and service resources such as digital signal processors (DSP) and open interconnects to media processing such as fax, conferencing and interactive voice response.
Switch Matrix. At the core of the programmable switch is a matrix that provides the actual timeslot interchange. For predictable call-handling performance, non-blocking architectures are preferred, so that all ports can have concurrent access through the network. This function moves a slot on a time-division multiplexed main bus from an input interface to an output interface. Through redundant matrices and features like error-detection, isolation, and automatic switch-over, the total switching function's vulnerability to a single matrix failure -- or any single point of failure - can be avoided. Scaling up fault tolerance from the card to the node to the network level enhances reliability of the entire infrastructure.
Line Interfaces. For configuration flexibility and network compatibility, line interfaces come in many different configurations -- from single line analog cards through multiple span T1/E1 cards. Key characteristics include ample provision for incremental growth in network usage and configuration; maximum capacity and performance; and the ability for resources to be freely mixed and matched to suit the service provider's need. Network flexibility built into open programmable switching platforms lets service providers deploy what's right for their interconnect needs today -- while not restricting them from growing to meet future demands.
Service Resources. Service resources represent a wide range of generally application-specific capabilities - such as SS7 services, sub-rate switching, ISDN Primary Rate Interfaces, DTMF tone generators and receivers, and conferencing. These resources may be resident in the switch chassis, or accessible via open interconnects such as bus extenders or interfaces.
Sophisticated switching designs can incorporate a timeslot interchange on each service resource, so in operation they consume neither network capacity nor switch ports on the main switching matrix. Desirable architectural characteristics of these resources include: seamless integration with the switch environment; configuration flexibility to mix and match resources; ability to hot-insert and remove while in operation; and provision for incremental growth. For example, a multi-function DSP resource which can be dynamically used for a wide variety of applications may be superior to a receiver attached to each port, or a service resource that is dedicated to providing tone receivers for one application only. By matching the resource architecture to the application needs, a user can greatly improve the cost-effectiveness of one architecture over another.
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Switching Features
The superior implementation of programmable switching hardware and software results in a number of beneficial features. With a knowledge of the range and extent of feature sets available, service providers can select a specific platform or architecture that is best suited to their needs. Generally the most significant features include:
Openness
One of the most important features in programmable switching is openness. From a software standpoint, openness gives the switch developer access to switching functionality through standard programming concepts and techniques such as: high level tools with GUI's, application program interfaces, and finite state machine definition and control. Openness also addresses adherence to industry standards - such as support for defined media resources -- and network interoperability, leveraging the service provider's investment by extending the utility of the switch in a variety of environments.
From a hardware standpoint, openness lets switch developers build and configure systems through design advantages like slot and device independence, component commonality and scalability. For example, by means of a modular architecture, powerful new technologies may be enabled without the necessity of system redesign. An open switching architecture that supports industry bus standards may freely allow the optimal distribution of switching resources throughout the infrastructure, enabling developers to implement features necessary for their own unique applications. As a result, they can bring new services to market rapidly and cost-effectively. Due to the ease and flexibility with which it can be adapted, tailored and used to deliver multiple service applications, the open programmable switch provides a very cost effective and versatile choice for implementing network infrastructure solutions in general.
Scalability
Scalability enables a single switching environment to fulfill a wide range of service needs, by upgrading or expanding for more capacity, functionality or performance as needed. The key benefit of a single scalable system is that it permits service providers to grow their deployments economically, efficiently and seamlessly, in step with demand. Scalable systems let providers avoid over-investment at start-up. They can commence with a small resource increment - appropriate and cost-effective for current need - and retain capacity for later growth. When market volume and/or requirements cost-justify growth in size or scope, new capacity can be added, new resources deployed and new services implemented as economically appropriate - a "dollar-for-value" investment. In the following dramatic illustration of scalability, the small switch module on the left, with under 100 ports and a footprint the size of a PC, scales directly to the 30,000 port environment on the right - utilizing the same API, switch matrix, interfaces, service resources and architecture.
The range of scalability reflects how expandable the system is - from both a physical and logical standpoint. Examples of physical limitations may be overall dimensions, number of slots or network connections. With a modular architecture, a single distributed switch environment can support tens of thousands of ports in a non-blocking manner. This wide range of scalability extends the value of a single architecture in dynamic and growing applications and gives service providers the ability to expand resources as needed, when needed.
Scalability performance reflects how linear expansion is. If the platform's architecture is sufficiently free of performance bottlenecks, then it is possible to achieve a proportional increase in performance and capacity as components are added. In other words, an increase in capacity will result in a relatively linear increase in throughput.
Ease of scalability defines how difficult it is to expand systems, and whether expansion will interrupt live operations. Systems can be difficult to scale or, through design competencies like hot insertion-and-removal and modularity, they can be easily scalable, even while in operation. Online expansion is particularly desirable in telecommunication voice applications, enabling services to be upgraded while the system is in operation, without interrupting service at all.
Configurability
In a manner similar to scalability, configurability focuses on a given system's ability to be configured and reconfigured easily and flexibly for a diverse range of applications. Important aspects of configurability are as follows.
Chassis design and layout are important for configuration flexibility. Slot, bus and device independence within a platform chassis adds flexibility in how a hardware configuration may be structured by allowing the free intermix of boards and other functional elements with minimal restrictions on their physical location or interconnection. Compatibility with industry standards and environments can further leverage the utility of switching resources by allowing them to be deployed where and when needed.
Modular components, subsystems or even entire platforms, having commonality across a variety of configurations, allow the service provider to minimize inventory, leverage equipment investment and promote technology re-use. Architectures with sufficient granularity permit precise matching of system size to need for optimal cost-effectiveness.
Performance density, if sufficiently high, lets providers build or plan large, high-performance systems within a small footprint. Technical features like multilayer PCBs, VLSI semiconductor technology, midplane chassis and superior thermal design permit configuration of more electronics per board and more boards per given space. The illustration below is an example of a programmable switch with a midplane chassis that mates supports multiple switch resource cards in a very space efficient manner. The result is as many as 1000 ports in a package with the footprint of a PC. This capability can greatly reduce the ancillary costs of facility development and environmental loading.
In summary, an open programmable switch gives service providers a resource that is as reliable, configurable and scalable - from a hardware standpoint - as it is open from a software standpoint.
Reliability
Because of the real-time nature of voice communications, the concept of reliability in switching is all-important. Reliability is a key factor in switching cost effectiveness. The more uptime that a given investment in hardware and software produces, the greater potential for revenue and profit as a result of that investment. Reliability has two primary metrics:
Availability is a measure of the ability of the switch or switching environment to remain continuously available for service, in operation, without interruption. Typical availability statistics are calibrated in MTBF (mean time between failure, usually hours) or as in uptime as a percentage of total time. The standard for select highly-reliable programmable switches is in the vicinity of 99.995 percent or greater.
Maintainability measures the ease and speed with which operation can be restored, should an interruption occur. It is often expressed by MTTR (mean time to repair, usually in minutes). Sophistication can cut MTTR to microseconds via an automatic and high-speed cascade of events: error detection, isolation of failed components and switch-over to back-up components. Maintainability is also extended by features that enable carriers to service or even expand equipment without interruption of operations. For example, the additional ability to hot-plug -- physically remove, replace or add components while the switch remains in operation -- can also enhance maintainability because it eliminates the need to power down the system.
Beyond pure numbers is the potential ability of the switch to tolerate a fault in a manner that is transparent to operation. It is generally enhanced by building in redundancy throughout the switch architecture. In redundancy, an extra component is incorporated into the system. It serves as a powered backup to the covered component. In the event of a fault, it can rapidly and automatically be brought into service. Redundancy can be applied to virtually any level in the switching environment: individual buses and chip components, switching matrices, circuit boards. In distributed architectures, entire switch chassis, resource node and fiber ring redundancy can be provided. Full 1+1 redundancy implements a one-for-one backup of each component and is commonly employed for critical functions served by a single component such as a switch matrix, signaling controller or fiber ring. In applications such as network interfacing where a collection of numerous identical components are deployed in a load sharing arrangement, N+1 redundancy can be a viable and cost effective alternative, by providing one back-up component per collection, for a total installed complement of functioning boards plus one.
Price Performance
Programmable switches can offer significant price performance advantages over earlier generation switching alternatives. Through distributed and scalable architectures, system resources like processing power, bus bandwidth and memory can be applied where it is needed. Sophisticated switching techniques distributed in service resources can further conserve ports for network operations. Because switching resources can be sized, configured and programmed to suit the application, high performance can be achieved cost-effectively.
Standards Compliance
By its very nature, programmable switching strongly implies adherence to standards. Standards in programmable switching apply not only to the openness of the switch environment itself, but also reflect compatibility to the standards required by the network infrastructure that the switching function is serving.
Network standards. Because the switch is a functional element in the infrastructure, it must comply with a variety of functional telecommunications standards, such as those that govern ISDN, SS7, T1 and E1. Compliance with country-specific standards, protocols and signaling variants are required for certification within a given locality. Examples include the ANSI and ITU standards, the European Union's CE Mark and a multitude of individual international standards and deltas such as the BABT in U.K. and JATE in Japan.
Regulatory requirements. In addition to telecommunications standards, the switch must generally comply with other technical specifications - such as electrical safety, heat output, radio frequency emissions, electrostatic discharge - published by government or industry regulatory bodies such as NEBS (Bellcore) and UL (Underwriter's Laboratories).
Device standards. In order to integrate host processing, switching and media resources such as voice processing devices, standards have been established to support their related bus architectures. Current defacto standard bus architectures include SCSA, MVIP and PEB; broader, industry-standards buses are likely to emerge in the future. Such standards enable a variety of board level devices to be compatible across different platforms. Recently the industry has taken a step further and begun to embrace interoperability between various architectures and APIs. A leading example of this effort is the Enterpise Computer Telephony Forum (ECTF), an industry organization whose family of Interoperability Agreements (IA's) are intended to accelerate deployment of CTI technology. For example, the H.100 specification has been proposed by the ECTF as an industry standard bus for media service resources.
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Benefits
The payoff of programmable switching is how it produces real-world economic benefits for service providers. These translate not only into immediate cost savings and enhanced return on investment, but also superior service, peace of mind and provision for the future:
Service Differentiation
With programmable switches, customization can be done on an application-by-application basis, thereby giving service providers the ability to differentiate their service from the competition, quickly and cost-effectively.
Matching Costs to Revenues
Often, promising new applications never make it to market because the initial investment may be deemed too high for unclear revenues. Programmable switching architectures can address this issue by evenly matching initial system sizing to initial revenue projections. Thus, new services can be deployed and market-tested cost effectively with minimal risk. Should demand for a new service take hold, a programmable switch-based platform will easily and cost-effectively scale to meet the service provider's needs.
Return on Investment
Through scalability, service providers need never outgrow their initial systems - nor lose their start-up investment. The system can be grown as the demand grows. And through openness and configurability, programmable switches have the versatility to provide a platform for multi-service applications. The programmable switch's ability to be tailored and adapted for the future protects current investments in the face of upcoming trends and uncertainties. As a result, there's no need to worry about having to write-off a piece of hardware long before it's depreciated. The risk of stranded investments that may occur with proprietary or inflexible alternatives is eliminated.
Programmable switches provide a superior return-on-investment for two primary reasons. First, because of outstanding price performance, they enable more capacity and throughput for a given investment. Thus, a service provider can support larger subscriber populations - and consequently, receive greater revenues - per configuration. Second, because the programmable switch is flexible and adaptable, it delivers a greater versatility of function per system. Thus the more utility available to the service provider, the greater the opportunity for additional revenues. The following illustration demonstrates the variety of functionality that, through chassis flexibility and programmability, can be deployed within a compact and open switch.
Reduced Time to Market
Programmable switches give service providers control of their own destiny. Even if service providers purchase third party applications, the openness of the platform gives them competitive choices, and enables the provider or third party developer to add new features or services at any time. The bottom line? Reduced time to market, lowered development costs, and a competitive edge in the marketplace.
Flexibility to Enhance the Application
The open architecture of a programmable switch allows the service provider to enhance an application rapidly, when needed. This flexibility allows the service provider to be in control of their own network and service offerings, meeting their customers' needs.
Flexible, Cost-effective Reliability
Reliability is a key issue in central office switching. The configurability of programmable switches provides cost-effective choices in this regard. Their architecture can be made as reliable as the application demands. Service providers can build extremely robust, fully redundant systems that provide the same hardware reliability as any existing alternative. Or, they can dramatically reduce costs while still providing high reliability by selecting the specific features that are appropriate to the application.
Deployability
Telecommunications infrastructure is expanding into remote regions worldwide. Programmable switching expedites and enhances this expansion by offering ease of configuration and maintenance, compact size, and local, open programmability. If programmability encompasses switching resources such as protocols for network interfaces, systems can be tailored to comply with widely varying local standards and protocols. And a distributed architecture makes it possible to deliver resources to remote nodes in the network, transparently, on demand. The result is added flexibility, versatility and performance in remote locations.
Furthermore, telecommunications in even highly industrialized nations are changing dramatically and possess many characteristics of emerging markets. Landline and wireless environments are evolving, enhanced services are spreading and competition is increasing. If carriers select a single open, programmable platform that supports broad standards and a variety of services, they can not only survive, but also thrive in the face of these developmental challenges and market demands.
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Programmable Switching Applications
Programmable switches provide cost-effective connectivity, network interfacing and access to service resources for a variety of telecommunications and telephony applications. They not only offer alternatives to traditional infrastructure but also make possible new functionality for enhanced service platforms. The use of this architecture has grown dramatically as service providers have begun to recognize the efficiency and the new revenue opportunities that result from application-specific solutions using off-the-shelf computer hardware. The three major markets, and consequently application areas, that are benefiting from programmable switching are:
Wireless Infrastructure
The growing domestic and international application of programmable switching in wireless applications reflect the expanding, dynamic and distributed characteristics of this market's major segments: wireless local loop and mobility. Programmable switching can fulfill the particular needs of new wireless service providers: rapid deployability, easy maintainability, cost-effectiveness, reduced time to market, and flexibility. As a result programmable switches are increasingly be found in the heart of the wireless infrastructure as base station controllers and mobile switching centers.
Particularly for wireless local loop applications that are often widely distributed and remote, it is essential that switching resources can be implemented efficiently at great distances and under often-rugged conditions. To the extent that it is modular, small in footprint, easily installed and supported by local service providers without the need for extensive switch manufacturer involvement, programmable switching fulfills this key requirement for this application.
Wireline Infrastructure
Deregulation of the wireline market, both domestically and internationally, has permitted hundreds of new carriers to begin offering services. Programmable switching lets them enter the market quickly and profitably, while enabling them to add new services as the market evolves. Within the wireline infrastructure, there are three categories of services upon which these new service providers can build: tandem switching, international gateways, and end-office switching. Although more tradition-bound than wireless, all these segments are also undergoing a dramatic market evolution and a blurring of their boundaries. In a manner typical of mature markets, price pressures have intensified as services such as POTS and bandwidth are viewed - and priced - as commodities. As a result, players need to achieve higher margins, provide one-stop shopping for their customers and minimize up-front entry costs. For example, service providers are now extending domestic long-distance to international networks. The Telecommunications Act of 1996 has made it possible for providers to actively pursue the same strategy in the local exchange.
Enhanced Service Platforms
The Enhanced Service Platform (ESP) segment is increasingly marked by a diversity of carrier services, applications and niches. Many enhanced services are interwoven with infrastructure applications. For example, voice-activated dialing is an attractive extension to wireless mobility offerings. Typical ESP services range from voice messaging to one number, to debit/prepaid calling card.
For large scale service providers, the consumption of network connections between the CO switch and the resources needed to implement voice processing services is an immediate and key issue. And for small scale deployments, capacity and scalability for future expansion is of equal concern. To the extent that programmable switching can be easily reconfigured, tailored and programmed, it can help ESP service providers tune their offerings for maximum appeal - to gain market share - and maximum cost-effectiveness -- to increase profitability and return on investment. And to the extent that programmable switching provides a versatile platform for multiple applications, it can give carriers both flexibility to offer a range of services and, consequently, enhanced financial strength through diversification.
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The Future of Programmable Switching
With the establishment of robust architectures and high performance products, programmable switching has proven itself throughout the network. Looking forward, the demand can only increase for the capability of programmable switching to support whatever standards, services and networks that may evolve in the future.
From a technology standpoint, programmable switching will continue to follow trends in the computer industry. Dramatic increases in price performance will mean more power, functionality and connectivity with the same size - or even smaller - cost and size envelope. The distinction between data and voice traffic will fade. Programmable switching will become even faster and easier to acquire, develop and deploy. The spread of open, industry standard architectures - including API's and bus specifications like H.100 -- and will enable service providers to build their own scalable and tailorable call processing models, optimized for the way they do business and for their subscribers' needs.
From a market standpoint, there will be a parallel demand for adaptable, flexible systems, driven by deregulation, worldwide deployment in remote areas and newly emerging services. As world economics progress and change, the ability for a service provider to offer low cost, high added-value and flexibility will be paramount for their success. Open programmable switching, with its ability to integrate software and hardware from different manufacturers gracefully, will enable the rapid deployment of differentiated services.
In summary the success of any programmable switch will be measured by its:
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ability to support, gracefully and cost-effectively, the addition of services and interfaces to the network; and |
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ability to evolve and grow to meet needs not yet even conceived. |
The only limits to open, programmable switching platforms are those of the imagination.
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Glossary of Acronyms
| API | application program interface
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| ANI | automatic number identification; caller ID function
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| CO | central office
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| CT | computer telephony
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| CTI | computer telephony integration
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| DS0 | a single, digitized voice conversation occupying 64Kbps of bandwidth
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| DSP | digital signal processing
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| DTMF | dual tone multi frequency; method of tone generation and signaling
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| E-1 | network line (or span) and interface capable of carrying 64 digitized voice
conversations; European standard
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| ESP | enhanced service platforms
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| GUI | graphical user interface
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| IN | intelligent network CT model
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| IP | intelligent peripheral component of IN
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| ISDN | integrated services digital network; extension of digital telephony to individual
subscribers
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| Kbps | thousands of bits per second
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| MTBF | mean time before failure
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| MTTR | mean time to repair
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| N+1 | A method of architectural fault tolerance in which an identical extra component is
available and pre-installed for in-service actuation
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| PBX | private branch exchange
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| POTS | colloquial: plain-old-telephone-service; basic dial-tone subscriber service
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| PSTN | public switched telephone network
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| SS7 | signaling system seven; method of out-of-band signaling
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| T-1 | network line (or span) and interface capable of carrying 64 digitized voice
conversations; U.S.standard
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| VLSI | very large scale integration; high density semiconductor technology
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| VP | voice processing |
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