Common Channel Interoffice Signaling Research Articles

The great blue box phone frauds

The use of an electronic device called the blue box to exploit a loophole in the nation's long-distance telephone network is recounted. To avoid long-distance charges, blue box users first dialed long-distance directory assistance, 800 numbers, or numbers that carried only a small toll charge. After the user dialed his number and was connected to a long-distance trunk, the blue box emitted a 2600 Hz tone, clearing the equipment at the tandem trunk's receiving end and signaling the switching equipment that the call had been completed and the trunk was waiting for a new call. The local central office, however, had not received its call termination signal, so the local central office did not disconnect the caller from the long-distance network. The permanent solution to the blue box problem proved to be common channel interoffice signaling (CCIS), a method rejected in the 1950s as too costly and difficult to implement.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Common Channel Signaling Network Evolution

This paper traces the evolution of the AT&T common channel signaling (CCS) network from its initial deployment as the common channel interoffice signaling (CCIS) network in 1976 to its present and future forms. Since the introduction of CCIS, the network has: added datagram direct-signaling capability, been reconfigured as a result of the AT&T divestiture, and been modernized by new digital and processor technology and by developments in software engineering techniques. In addition, the CCS network has become a key part of the AT&T service architecture, allowing faster nationwide deployment of services. The globalization and further functional enhancements of the network are also discussed.

Realization of a Signaling System No. 7 Network for AT&amp;amp;T

Transition of the AT&T Communications Common Channel Interoffice Signaling (CCIS) Network, currently the world's largest, to a more powerful and flexible network with Common Channel Signaling System No. 7 capability has begun with the introduction of a more powerful signaling transfer point system and high-speed data links. The evolving AT&T network will be a key element in supporting an Integrated Services Digital Network (ISDN) capability. This paper describes the status of the existing AT&T CCIS network and how it will evolve toward a new network employing Signaling System No. 7 utilizing the ISDN User part (ISDN-UP). It also considers Signaling System No. 7 ISDN-UP implementation and the flexibility of the ISDNUP protocol in support of future customer needs.

Stored Program Controlled Network: Routing of Direct-Signaling Messages in the CCIS Network

This paper compares and contrasts the two methods currently used to route messages through the common-channel interoffice signaling (CCIS) network. Since its introduction in 1976, the CCIS network has been providing routing of telephone signaling messages between switching offices using permanent virtual circuits. In 1980, a new datagram routing capability, called direct signaling, has been added that significantly enhances the network's ability to interconnect Stored Program Control (SPC) systems. Stored program control systems interconnected by the signaling network can now communicate in support of improved SPC network services in addition to CCIS trunk-related call-control signaling. This paper briefly reviews banded telephone routing and then describes and compares direct signaling routing. The new flow control procedures required to implement direct signaling are discussed and two examples of applications using direct signaling are presented.

Stored Program Controlled Network: CCIS and SPC Network Performance

Common-channel interoffice signaling (CCIS) represents a major advance in interoffice signaling speed and capability over current inband signaling systems. The introduction of CCIS between Stored Program Control (SPC) switching offices is reducing ineffective machine attempts (IMAS) caused by transmission and switching irregularities associated with inband signaling. Because signaling between CCIS-equipped switching offices is concentrated in a relatively small number of signaling links and signal transfer points (STPS), a high standard of performance for the signaling network is essential. Therefore, the design of the signaling network incorporates many features to assure a high degree of availability. Cumulative data on STPS and studies of signaling links are the principal measures of signaling network performance. Data on their performance are presented that confirm the high availability of the signaling network.

Stored Program Controlled Network: Prologue

The rapid introduction of electronic switching systems with Stored Program Control (SPC) has made possible the interconnection of the control processors by high-speed data links to provide common-channel interoffice signaling (CCIS). Not only does this permit higher-speed, lower-cost, more reliable setup of connections, but also the transfer of packets of information for more flexible call control. The papers in this issue describe the evolution of the SPC network concept since the introduction of CCIS in 1976 and the first new services which will exploit the power of this new network capability.

Stored Program Controlled Network: NO. 1/1A ESS-SPC Network Capabilities and Signaling Architecture

The No. 1/1A Electronic Switching System (ESS) will play an important role in the evolving Stored Program Controlled (SPC) Network because, as a major electronic switching system for local and combined local/toll service, it provides direct interfaces to many of the Bell System's customers. It provides important capabilities required for System 800 Service and for a variety of other new SPC network services. This paper describes several of the basic SPC network capabilities provided by the No. 1/1A ESS. It also describes the architecture and implementation of its common-channel interoffice signaling (CCIS) subsystem, CCIS call-processing software, and System 800 software.

Stored Program Controlled Network: Generic Network Plan

The network of stored program control communication processors interconnected with common-channel interoffice signaling (CCIS) is commonly referred to as the Stored Program Controlled (SPC) Network. The SPC network will result in new call handling and routing improvements and in new network-based services. It is desirable to tailor the services to meet special customer needs and to deploy them rapidly. A generic plan is described which provides a basis for building services from basic functional capabilities that are deployed in network action points and controlled by network control points. Terminating-end office features can be used to provide additional customer service options. Thus, service for a customer can be composed of sequences of actions stored at appropriate network central points using basic switching capabilities deployed in the network. As needs for customer service evolve, new capabilities can be added to the repertoire of existing capabilities. By equipping key nodes with the capabilities described, the generic plan will also allow the SPC network to evolve efficiently to meet future customer needs.

Stored Program Controlled Network: Overview

This paper describes the evolution and architecture of the Stored Program Controlled (SPC) Network. The critical role of common-channel interoffice signaling (CCIS) is discussed, both as an improved method for providing the traditional signaling functions, and as the key to a wide range of new service opportunities. These are made possible by the ability to interrupt call progress and, in real-time, interrogate a distant data base and modify the subsequent call handling based on the information returned. The underlying architecture by which these services are implemented is based on the objectives of providing ubiquitous service with limited deployment of essential network capabilities and creating a structure which permits customized services by modifying the contents of a centralized data base.

Effect of Echo Canceler on Common-Channel Interoffice Signaling Continuity Check

Annoying echoes generated by impedance mismatches can occur in long-distance telephone networks. An echo canceler controls echo by synthesizing an echo replica and subtracting it from the actual echo on the return path. For the echo canceler to work properly, it must be able to distinguish between desired signals and echoes. One instance where this can be difficult is during the common-channel interoffice signaling (CCIS) continuity check between four-wire switching offices. On OCXS trunks the voice and the signaling are routed separately. To ensure a satisfactory transmission path, a voice path continuity check is conducted before call setup. The check is performed on a loop basis by sending a check tone and looping it back at the distant office. Since the echo canceler adaptive filter memorizes information from the last previous call, it may partially cancel the looped-back tone. In this paper we study the effect of the echo canceler adaptive memory on the CCIS continuity check. The analytical and experimental results indicate that the occurrence of continuity check failure caused by the presence of an active echo canceler is so infrequent and insignificant compared to the existing statistics of all other pertinent failure mechanisms. Thus, disabling the echo canceler during the CCIS continuity check is unnecessary.

Network Management and Congestion in the U.S. Telecommunications Network

Several significant steps have been taken to respond to the need for better network management for the evolving U.S. telecommunications network. The current approach provides an economical balance between automatic and manual network management capabilities. With the rapid introduction of Stored Program Controlled (SPC) switching systems and the Common Channel Interoffice Signaling (CCIS) system, more emphasis is being placed on continued improvement in automatic controls. Advances in manual network management controls and real-time surveillance capabilities have been accomplished primarily through the introduction of computer-based systems which support the operation of centralized Network Management Centers (NMC's). Also, new controls are introduced for forthcoming SPC-CCIS network services. The evolution, status, and future needs for network management of the coterminous U.S. telecommunications network are presented. An extensive bibliography is given.

Measuring the Utilization of a Synchronous Data Link: An Application of Busy-Period Analysis

The utilization of links in a communication network is an important and easily measurable quantity; it is the fraction of time that a link is busy. We focus on the estimation of link utilization through measurements and consider, in particular, the duration of measurement required for a prescribed accuracy of the estimate. Two conflicting factors involved in the choice of measurement time are the desirability of a measurement of short, and thus recent, duration and the desirability of an interval of sufficient duration to assure statistical accuracy. We assume that the composite input of messages to an outgoing buffer of a synchronous data link constitutes a Poisson process. The message length is arbitrarily distributed and is in units of “packets.” This allows us to model the transmission facilities as a continuous-time-input, discrete-time-output M | G | 1 queue. We analyze the output process of such a system and determine the time needed to measure link utilization with a prescribed accuracy. We also present an application to the Common Channel Interoffice Signaling network as an illustration of the analysis.

Common Channel Interoffice Signaling: No. 4 ESS Application

Common channel interoffice signaling (CCIS) is provided as an integral part of No. 4 ESS. The unique hardware required for CCIS consists of a common systems CCIS terminal and associated access circuit, continuity check transceivers, and unitized terminal equipment for CCIS trunks. The control of the CCIS hardware and the logic required for CCIS administrative functions is provided by programs resident in the 1A Processor. This paper discusses the system design requirements, the signaling hardware, and the software design for CCIS in the No. 4 Electronic Switching System.

Common Channel Interoffice Signaling: Implementation Planning

To introduce Common Channel Interoffice Signaling (CCIS) into the toll network as rapidly and economically as possible, a great deal of planning had to be done. An analysis was performed to determine which 4A-ETS (Electronic Translation System) offices should be converted to CCIS and the order of this conversion. Practical feasibility constraints also had to be considered. This analysis was followed by coordination with AT&T and the operating companies which resulted in a plan to convert about thirty 4A-ETS switching offices per year to CCIS in 1977, 1978, and 1979. In addition, all No. 4 ESS offices are CCIS-equipped and No. 1 (A) ESS will be CCIS-equipped by 1978. The result is that by 1980 more than a hundred toll offices will have CCIS capability.

Common Channel Interoffice Signaling: Peripheral Maintenance and Administration Support System

Common Channel Interoffice Signaling (CCIS) introduces a new network for routing signaling information, new equipment, and new functions for which performance must be monitored. Reliable, timely (within seconds or minutes in many cases), and readily usable performance reports are required by traffic and maintenance personnel to administer and maintain these new capabilities to provide the high quality of service to which customers are accustomed. The Peripheral Bus Computer (PBC) System provides the maintenance and administration support required by the CCIS signaling network, Signal Transfer Point (STP) offices, and toll crossbar switching offices. This article describes the PBC and the support it provides CCIS.

Common Channel Interoffice Signaling: Development Tools

Tools used in the design, development, and testing of various components of the Common Channel Interoffice Signaling (CCIS) feature of No. 4A toll crossbar and No. 4 ESS are described. Included in the discussion are CCIS software design and administration support tools, electronic circuit design, analysis, and test tools, and laboratory support systems for software and hardware testing.

Common Channel Interoffice Signaling: Technology and Hardware

The CCIS hardware is a mix of electromechanical, discrete electronic, and new integrated electronic technologies blended together to allow economical conversion of No. 4A/ETS offices while at the same time matching the technology of the electronic toll offices in which it is incorporated. Connectorization and plug-in assemblies help achieve a design that can be readily maintained and administered.

Common Channel Interoffice Signaling: History and Description of a New Signaling System

A new interoffice signaling system known as the Common Channel Interoffice Signaling System (CCIS) has been introduced into the Bell System's DDD toll network. It represents a major step forward in signaling systems by providing high speed data links between processors of stored-program-controlled switching offices to carry all signaling and network control information, completely independent of the communication paths used by customers. As CCIS implementation proceeds it will have an expanding and significant impact on the DDD network system performance due to improved speed of signaling and provision of signals to provide a multitude of new network and customer services. The history of common channel signaling is traced from early mechanical implementation to use of present-day technological advances. The fundamental concepts, basic features, signal formats and system operation are described.

No.4 ESS: Peripheral System

The No. 4 ess peripheral system economically performs essential switching and signaling functions. A modern time-division switching network has been developed to meet rapidly growing traffic demands and provide a basis for the all-electronic telecommunications network of the future. Common-channel interoffice signaling (ccis) provides high-speed interprocessor communication via data link. Signal processor units perform routine signaling tasks such as scanning and digit collection, effectively increasing the main processor's capacity. To a greater degree than in previous systems, the vital man-machine interfaces are enhanced with sophisticated interactive capability.