INTERNATIONAL TELECOMMUNICATION UNION
`
`
`
`CCITT
`
`THE INTERNATIONAL
`TELEGRAPH AND TELEPHONE
`CONSULTATIVE COMMITTEE
`
`Q.700
`
`(11/1988)
`
`SERIES Q: SWITCHING AND SIGNALLING
`Specifications of Signalling System No. 7 – General
`
`
`INTRODUCTION TO CCITT SIGNALLING
`SYSTEM No. 7
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`Reedition of CCITT Recommendation Q.700 published in
`the Blue Book, Fascicle VI.7 (1988)
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`Ex. 1017
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`NOTES
`CCITT Recommendation Q.700 was published in Fascicle VI.7 of the Blue Book. This file is an extract from
`1
`the Blue Book. While the presentation and layout of the text might be slightly different from the Blue Book version, the
`contents of the file are identical to the Blue Book version and copyright conditions remain unchanged (see below).
`2
`In this Recommendation, the expression “Administration” is used for conciseness to indicate both a
`telecommunication administration and a recognized operating agency.
`
`
`
`© ITU 1988, 2008
`All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written
`permission of ITU.
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`Ex. 1017
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`Recommendation Q.700
`
`
`INTRODUCTION TO CCITT SIGNALLING SYSTEM No. 7
`
`General
`1
`This Recommendation provides an overview of the Signalling System by describing the various functional
`
`elements of CCITT No. 7 and the relationship between these functional elements. This Recommendation provides a
`general description of functions and capabilities of the Message Transfer Part (MTP), Signalling Connection Control Part
`(SCCP), Telephone User Part, ISDN User Part (ISDN-UP), Transaction Capabilities (TC), and the Operations,
`Maintenance and Administration Part (OMAP) which are covered elsewhere in the Q.700 to Q.795 series of
`Recommendations. However, in the case of contradiction between the specifications and Q.700, the Q.700 to Q.795
`specification shall apply.
`
`Supplementary Services in CCITT S.S. No.7 ISDN applications are described in the Q.73x series of
`Recommendations.
`
`In addition to these functions in the CCITT No. 7 signalling system, the Q.700 to Q.795 series of
`Recommendations describes the CCITT No. 7 network structure, and also specifies the Tests and Measurements
`applicable to CCITT No. 7.
`
`This Recommendation is also a specification of those aspects such as CCITT S.S. No. 7 Architecture, Flow
`Control and general compatibility rule which are not specified in separate Recommendations, and are applicable to the
`overall scope of S.S. No. 7.
`
`The remainder of this Recommendation describes:
`– § 2: Signalling network concepts components and modes;
`– § 3: The functional blocks within CCITT Signalling System No. 7 and the services provided by them;
`– § 4: CCITT Signalling System No. 7 protocol layering and its relationship to OSI modelling;
`– § 5: Node, application entity and user part addressing;
`– § 6: Operations, administration and maintenance aspects of CCITT S.S. No. 7;
`– § 7: Performance aspects of the functional blocks within CCITT S.S. No. 7;
`– § 8: Flow control for both the signalling network and within nodes;
`– § 9: Rules for evolving CCITT S.S. No. 7 protocols while preserving compatibility with earlier versions;
`– § 10: A cross-reference to a glossary of terms.
`
`–
`
`–
`
`Objectives and fields of application
`1.1
`The overall objective of Signalling System No. 7 is to provide an internationally standardised general purpose
`
`common channel signalling (CCS) system:
`– optimised for operation in digital telecommunications networks in conjunction with stored program
`controlled exchanges;
`that can meet present and future requirements of information transfer for inter-processor transactions
`within telecommunications networks for call control, remote control, and management and maintenance
`signalling;
`that provides a reliable means for transfer of information in correct sequence and without loss or
`duplication.
`The signalling system meets requirements of call control signalling for telecommunication services such as the
`
`telephone, ISDN and circuit switched data transmission services. It can also be used as a reliable transport system for
`other types of information transfer between exchanges and specialised centres in telecommunications networks (e.g. for
`management and maintenance purposes). The system is thus applicable for multipurpose uses in networks that are
`dedicated for particular services and in multiservices networks. The signalling system is intended to be be applicable in
`international and national networks.
`
`The scope of CCITT S.S. No. 7 encompasses both circuit related and non-circuit related signalling.
`
`Examples of applications supported by CCITT S.S. No. 7 are:
`– PSTN,
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`
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`Fascicle VI.7 – Rec. Q.700
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`1
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`ISDN,
`–
`Interaction with Network Databases, Service Control Points for service control,
`–
`– Mobiles (Public Land Mobile Network),
`– Operations Administration and Maintenance of Networks.
`The signalling system is optimized for operation over 64-kbit/s digital channels. It is also suitable for operation
`
`over analogue channels and at lower speeds. The system is suitable for use on point-to-point terrestrial and satellite links.
`It does not include the special features required for use in point-to-multipoint operation but can, if required, be extended
`to cover such an application.
`
`General characteristics
`1.2
`Common channel signalling is a signalling method in which a single channel conveys, by means of labelled
`
`messages, signalling information relating to, for example, a multiplicity of circuits, or other information such as that used
`for network management. Common channel signalling can be regarded as a form of data communication that is
`specialised for various types of signalling and information transfer between processors in telecommunications networks.
`
`The signalling system uses signalling links for transfer of signalling messages between exchanges or other
`nodes in the telecommunication network served by the system. Arrangements are provided to ensure reliable transfer of
`signalling information in the presence of transmission disturbances or network failures. These include error detection and
`correction on each signalling link. The system is normally applied with redundancy of signalling links and it includes
`functions for automatic diversion of signalling traffic to alternative paths in case of link failures. The capacity and
`reliability for signalling may thus be dimensioned by provision of a multiplicity of signalling links according to the
`requirements of each application.
`
`Components of CCITT S.S. No. 7
`1.3
`CCITT S.S. No. 7 consists of a number of components or functions which are defined as a series of Q.700
`
`to Q.795 Recommendations.
`Recommendations
`
`CCITT S.S. No. 7 function
`
`Q.701-Q.704, Q.706, Q.707
`Message Transfer Part (MTP)
`
`Q.721-Q.725
`Telephone User Part (TUP) (including supplementary services)
`
`Q.730
`Supplementary services
`
`Q.741 (note 1)
`Data User Part (DUP)
`
`Q.761-Q.764, Q.766
`ISDN User Part (ISDN-UP)
`
`Q.711-Q.714, Q.716
`Signalling Connection Control Part (SCCP)
`
`Q.771-Q.775
`Transaction Capabilities (TC)
`
`Q.795
`Operations Maintenance and Administration Part (OMAP)
`Note 1 – Functions of the DUP are fully specified in Recommendation X.61.
`
`
`Other Q.700 to Q.795 series Recommendations which describe other aspects of the signalling system but not
`part of the CCITT S.S. No. 7 signalling interfaces are:
`
`Title
`
`Signalling Network Structure
`
`Numbering of International Signalling Point Codes
`
`Hypothetical signalling reference connection
`
`PABX application
`
`CCITT S.S. No. 7 Test Specification (General)
`
`MTP Level 2 Test Specification
`
`MTP Level 3 Test Specification
`
`TUP Test Specification
`
`Monitoring and measurements for the CCITT S.S. No.7 network
`
`Recommendations
`Q.705
`Q.708
`Q.709
`Q.710
`Q.780
`Q.781
`Q.782
`Q.783
`Q.791
`
`2
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`Fascicle VI.7 – Rec. Q.700
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`§ 3 of Q.700 describes the relationship between these components.
`
`
`
`Description techniques in the Q.700 to Q.795 series of Recommendations
`1.4
`The CCITT S.S. No. 7 Recommendation series define the signalling system using prose description which is
`
`complemented by SDL diagrams and state transition diagrams. Should any conflict arise between the text and the SDL
`definition, the textual description is taken as definitive.
`
`Message sequence charts or arrow diagrams are used to illustrate examples of signalling procedures, but are
`not considered definitive.
`
`2
`
`CCITT S.S. No. 7 signalling network
`
`Basic concepts
`2.1
`A telecommunications network served by common channel signalling is composed of a number of switching
`
`and processing nodes inter-connected by transmission links. To communicate using CCITT No. 7, each of these nodes
`requires to implement the necessary “within node” features of CCITT S.S. No. 7 making that node a signalling point
`within the CCITT S.S. No. 7 network. In addition, there will be a need to interconnect these signalling points such that
`CCITT S.S. No. 7 signalling information (data) may be conveyed between them. These data links are the signalling links
`of CCITT S.S. No. 7 signalling network.
`
`The combination of signalling points and their interconnecting signalling links form the CCITT S.S. No. 7
`signalling network.
`
`Signalling network components
`2.2
`Signalling points
`2.2.1
`In specific cases there may be a need to partition the common channel signalling functions at such a (physical)
`
`node into logically separate entities from a signalling network point of view; i.e., a given (physical) node may be defined
`as more than one signalling point. One example is an exchange at the boundary between international and national
`signalling networks.
`
`Any two signalling points, for which the possibility of communication between their corresponding User Part
`function exists, are said to have a signalling relation.
`
`The corresponding concept for a given User Part is called a user signalling relation.
`
`An example is when two telephone exchanges are directly connected by a bundle of speech circuits. The
`exchange of telephone signalling relating to these circuits then constitutes a user signalling relation between the
`Telephone User Part functions in those exchanges in their role as signalling points.
`
`Another example is when administration of customer and routing data in a telephone exchange is remotely
`controlled from an operation and maintenance centre by means of communication through a common channel signalling
`system.
`
`
`Examples of nodes in a signalling network that constitutes signalling points are:
`–
`exchanges (switching centres),
`– operation, administration and maintenance centres,
`–
`service control points,
`–
`signalling transfer points.
`All signalling points in a CCITT S.S. No. 7 network are identified by a unique code known as a point code
`
`(Recommendation Q.704 refers).
`Signalling links
`2.2.2
`
`The common channel signalling system uses signalling links to convey the signalling messages between two
`signalling points. A number of signalling links that directly interconnect two signalling points which are used as a
`module constitute a signalling link-set. Although a link set typically includes all parallel signalling links, it is possible to
`use more than one link set in parallel between two signalling points. A group of links within a link set that have identical
`characteristics (e.g., the same data link bearer rate) is called a link group.
`
`
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`Fascicle VI.7 – Rec. Q.700
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`3
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`Two signalling points that are directly interconnected by a signalling link are, from a signalling network
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`structure point of view, referred to as adjacent signalling points. Correspondingly, two signalling points that are not
`directly interconnected are non-adjacent signalling points.
`Signalling modes
`2.2.3
`
`The term “signalling mode” refers to the association between the path taken by a signalling message and the
`signalling relation to which the message refers.
`
`In the associated mode of signalling, the messages relating to a particular signalling relation between two
`adjacent points are conveyed over a link set, directly interconnecting those signalling points.
`
`In the non-associated mode of signalling, the messages relating to a particular signalling relation are conveyed
`over two or more linksets in tandem passing through one or more signalling points other than those which are the origin
`and the destination of the messages.
`
`The quasi-associated mode of signalling is a limited case of the non-associated mode where the path taken by
`the message through the signalling network is pre-determined and, at a given point in time, fixed.
`
`Signalling System No. 7 is specified for use in the associated and quasi-associated modes. The Message
`Transfer Part does not include features to avoid out-of-sequence arrival of messages or other problems that would
`typically arise in a fully non-associated mode of signalling with dynamic message routing.
`
`Examples of signalling modes are illustrated in Figure 1/Q.700.
`
`FIGURE 1/Q.700
`Examples of associated and quasi-associated signalling modes and
`definition of signalling network graph symbols
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`
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`Signalling point modes
`2.3
`A signalling point at which a message is generated, i.e., the location of the source User Part function, is the
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`originating point of that message.
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`A signalling point to which a message is destined, i.e., the location of the receiving User Part function, is the
`destination point of that message.
`
`A signalling point at which a message is received on a signalling link is transferred to another link, i.e., neither
`the location of the source nor the receiving User part function, is a Signal Transfer Point (STP).
`
`For a particular signalling relation, the two signalling points thus function as originating and destination points
`for the messages exchanged in the two directions between them.
`
`In the quasi-associated mode, the function of a signalling transfer point is typically located in a few signalling
`points which may be dedicated to this function, or may combine this function with some other (e.g., switching) function.
`A signalling point serving as a signalling transfer point functions as an originating and destination point for the messages
`generated and received by the level 3 function of the Message Transfer Point also in cases when no user functions are
`present.
`
`4
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`Fascicle VI.7 – Rec. Q.700
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`Signalling routes
`2.4
`The pre-determined path, consisting of a succession of signalling points/signalling transfer points and the
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`interconnecting signalling links, that a message takes through the signalling network between the origination point and
`the destination point is the signalling route for that signalling relation.
`
`All the signalling routes that may be used between an originating point and a destination point by a message
`traversing the signalling network is the signalling route set for that signalling relation.
`
`Signalling network structure
`2.5
`The signalling system may be used with different types of signalling network structures. The choice between
`
`different types of signalling network structures may be influenced by factors such as the structure of the
`telecommunication network to be served by the signalling system and administrative aspects.
`
`In the case when the provision of the signalling system is planned purely on a per signalling relation basis, the
`likely result is a signalling network largely based on associated signalling, typically supplemented by a limited degree of
`quasi-associated signalling for low volume signalling relations. The structure of such a signalling network is mainly
`determined by the patterns of the signalling relations.
`
`Another approach is to consider the signalling network as a common resource that should be planned according
`to the total needs for common channel signalling. The high capacity of digital signalling links in combination with the
`needs for redundancy for reliability then typically leads to a signalling network based on a high degree of quasi-
`associated signalling with some provision for associated signalling for high volume signalling relations. The latter
`approach to signalling network planning is more likely to allow exploitation of the potential of common channel
`signalling to support network features that require communication for purposes other than the switching of connections.
`
`The worldwide signalling network is structured into two functionally independent levels, namely the
`international and national levels. This structure makes possible a clear division of responsibility for signalling network
`management and allows numbering plans of signalling points of the international network and the different national
`networks to be independent of one another.
`
`Further considerations about the structure of the signalling network are given in Recommendation Q.705, and
`the impact on the message transfer part in Recommendation Q.701.
`
`3
`
`CCITT S.S. No. 7 functional blocks
`
`3.1
`
`
`Basic functional division
`The Blue Book CCITT Signalling System No. 7 comprises the following functional blocks:
`– Message Transfer Part
`
`
`(MTP)
`– Telephone User Part
`
`
`(TUP)
`–
`ISDN User Part
`
`
`
`(ISDN-UP)
`– Signalling Connection Control Part
`
`(SCCP)
`– Transaction Capabilities
`
`
`(TC)
`(AE) Note 1
`– Application-Entity
`
`
`
`(ASEs) Note 1
`– Application-Service-Elements
`
`Note 1 – The glossary shows these as hyphenated terms but the usual convention used in this Recommendation
`
`will be unhyphenated.
`
`The fundamental principle of the signalling system structure is the division of functions into a common
`Message Transfer Part (MTP) on one hand, and separate User Parts for different users on the other. This is illustrated in
`Figure 2/Q.700.
`
`The overall function of the Message Transfer Part is to serve as a transport system providing reliable transfer of
`signalling messages between the locations of communicating user functions.
`
`User functions in CCITT S.S. No. 7 MTP terms are:
`–
`the ISDN User Part
`
`
`
`–
`the Telephone User Part
`
`
`–
`the Signalling Connection Control Part
`
`(ISDN-UP)
`(TUP)
`(SCCP)
`
`
`
`
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`Fascicle VI.7 – Rec. Q.700
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`(DUP)
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`
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`the Data User Part
`–
`The term “User” in this context refers to any functional entity that utilises the transport capability provided by
`
`the Message Transfer Part.
`
`A User Part comprises those functions of, or related to, a particular type of user that are part of the common
`channel signalling system, typically because those functions need to be specified in a signalling context.
`
`The SCCP also has Users. These are:
`–
`the ISDN User Part
`
`
`– Transaction Capabilities
`
`
`(ISDN-UP)
`(TC)
`
`
`
`
`FIGURE 2/Q.700
`Architecture of CCITT SS No. 7
`
`
`
`CCITT S.S. No. 7 architecture
`3.2
`General
`3.2.1
`Figure 2/Q.700 shows the Architecture of CCITT S.S. No. 7 and illustrates the functional relationship between
`
`the various functional blocks of the Blue Book CCITT S.S. No. 7. Figure 5/Q.700 shows the relationship between
`CCITT No. 7 levels and the OSI Reference Model Layers. This level/layer relationship is described in the following
`sections.
`The initial specification of CCITT No. 7 was based on circuit-related telephony control requirements. To meet
`
`these requirements, CCITT No. 7 was specified in four functional levels, the Message Transfer Part comprising levels
`1-3, and the User Parts as level 4.
`
`Figure 3/Q.700 shows the Functional Levels of CCITT S.S. No. 7. As new requirements have emerged, e.g.,
`for non-circuit related information transfer, CCITT S.S. No. 7 has also evolved to meet these new requirements. There
`has been a need to align certain elements in CCITT No. 7 to the OSI 7 Layer Reference Model.
`
`The result of this evolution is that Functional Levels and OSI layers co-exist in CCITT No. 7. For example, the
`SCCP is a level 4 User Part in MTP terms, but also provides an OSI Network layer 3 service. Subsequent sections
`describe the various functional elements of CCITT S.S. No. 7 in terms of levels and layers.
`
`6
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`Fascicle VI.7 – Rec. Q.700
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`FIGURE 3/Q.700
`CCITT No.7 funcional levels
`It should be noted that the approach proposed for ISDN architecture is to define two orthogonal planes, User
`
`and Control, each of which has its own 7-layer protocol reference model.
`
`From the perspective of an end user, the service provided by a telecommunications network may be regarded
`as a Network Layer Service (User Plane).
`
`Within the telecommunications network, the techniques of the ISDN Protocol Reference Model are applied,
`and the 7-layer protocol structure of the OSI Model can also be used for inter-nodal communication to the end user.
`Message Transfer Part (MTP) levels 1-3
`3.2.2
`
`An overview of the MTP is given in Recommendation Q.701. The MTP is defined in Recommendations
`Q.701-Q.704, Q.706 and Q.707.
`3.2.2.1 Signalling data link functions (level 1)
`
`Level 1 defines the physical, electrical and functional characteristics of a signalling data link and the means to
`access it. The level 1 element provides a bearer for a signalling link.
`
`In a digital environment, 64-kbit/s digital paths will normally be used for the signalling data link. The
`signalling data link may be accessed via a switching function, providing a potential for automatic reconfiguration of
`signalling links. Other types of data links, such as analogue links with modems, can also be used.
`
`The detailed requirements for signalling data links are specified in Recommendation Q.702.
`3.2.2.2 Signalling link functions (level 2)
`
`Level 2 defines the functions and procedures for and relating to the transfer of signalling messages over one
`individual signalling data link. The level 2 functions together with a level 1 signalling data link as a bearer, and provides
`a signalling link for reliable transfer of signalling messages between two points.
`
`A signalling message delivered by the higher levels is transferred over the signalling link in variable length
`signal units. For proper operation of the signalling link, the signal unit comprises transfer control information in addition
`to the information content of the signalling message.
`
`The detailed requirements for signalling functions are given in Recommendation Q.703.
`3.2.2.3 Signalling network functions (level 3)
`
`Level 3 in principle defines those transport functions and procedures that are common to and independent of
`the operation of individual signalling links. These functions fall into two major categories:
`a) Signalling message handling functions - These are functions that, at the actual transfer of the message,
`direct the message to the proper signalling link or User Part.
`b) Signalling network management functions - These are functions that, on the basis of predetermined data
`and information about the status of the signalling network, control the current message routing and
`configuration of the signalling network facilities. In the event of changes in the status, they also control the
`reconfigurations and other actions to preserve or restore the normal message transfer capability.
`The detailed requirements for signalling network functions are given in Recommendation Q.704.
`
`
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`Fascicle VI.7 – Rec. Q.700
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`Level 4: MTP User functions
`3.2.3
`Level 4 consists of the different User Parts. Each User Part defines the functions and procedures of the
`
`signalling system that are particular to a certain type of user of the system. the following entities are defined as User
`Parts in CCITT S.S. No. 7.
`3.2.3.1 Signalling Connection Control Part (SCCP)
`
`The SCCP is defined in Recommendations Q.711-Q.716. This Recommendation series defines the SCCP
`capabilities, layer interfaces to MTP and SCCP users signalling messages, their encoding and signalling procedures, and
`cross-office performance. The SCCP provides additional functions to the Message Transfer Part to provide such
`connectionless and connection-oriented network services to transfer circuit-related, and non-circuit-related signalling
`information.
`
`The SCCP provides the means to:
`–
`control logical signalling connections in a CCITT No. 7 network;
`– Transfer Signalling Data Units across the CCITT No. 7 network with or without the use of logical
`signalling connections.
`SCCP provides a routing function which allows signalling messages to be routed to a signalling point based on,
`
`for example, dialled digits. This capability involves a translation function which translates the global title (e.g., dialled
`digits) into a signalling point code and a subsystem number.
`
`SCCP also provides a management function, which controls the availability of the “subsystems”, and
`broadcasts this information to other nodes in the network which have a need to know the status of the “subsystem”.
`
`The combination of the MTP and the SCCP is called “Network Service Part” (NSP). The Network Service Part
`meets the requirements for layer 3 services as defined in the OSI-Reference Model, CCITT Recommendation X.200.
`3.2.3.2 Telephone User Part (TUP)
`
`The CCITT S.S. No. 7 Telephone User Part is defined in Recommendations Q.721-725. The TUP
`Recommendations define the necessary telephone signalling functions for use of S.S. No. 7 for international telephone
`call control signalling. This Recommendation series defines the telephone signalling messages, their encoding and
`signalling procedures, and cross-office performance.
`
`Supplementary Services handled by the CCITT S.S. No. 7 TUP applications are described in Recommendation
`Q.724, § 10. These supplementary services embody TUP signalling messages and procedures.
`3.2.3.3 Data User Part (DUP)
`
`The Data User Part is defined in Recommendation Q.741, and the functionality fully defined in
`Recommendation X.61. It defines the protocol to control interexchange circuits used on data calls, and data call facility
`registration and cancellation.
`ISDN User Part (ISDN-UP)
`3.2.3.4
`
`The ISDN User Part is defined in Recommendations Q.761-Q.764 and Q.766. This Recommendation series
`defines the ISDN network signalling messages, their encoding and signalling procedures, and cross-office performance.
`This Recommendation series deals with the basic services only.
`
`The ISDN-UP encompasses signalling functions required to provide switched services and user facilities for
`voice and non-voice applications in the ISDN.
`
`The ISDN-UP is also suited for application in dedicated telephone and circuit-switched data networks and in
`analogue, and mixed analogue/digital networks.
`
`The ISDN-UP has an interface to the SCCP (which is also a level 4 User Part) to allow the ISDN-UP to use the
`SCCP for end-to-end signalling.
`
`Supplementary Services handled by the CCITT S.S. No. 7 ISDN application are described in Recommendation
`Q.730. These supplementary services embody ISDN-UP signalling messages and procedures. In some cases these
`services also include application protocol which uses TC and SCCP, as, for example, centralised Closed User Group
`(CUG).
`3.2.3.5 Transaction Capabilities
`
`Transaction Capabilities is defined in Recommendations Q.771-Q.775. This Recommendation series defines
`the Transaction Capabilities signalling messages, their encoding and signalling procedures.
`
`8
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`Fascicle VI.7 – Rec. Q.700
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`TC provides the means to establish non-circuit-related communication between two nodes in the signalling
`
`Transaction Capabilities consists of two elements. These are:
`– Transaction Capabilities Application Part (TCAP);
`–
`Intermediate Service Part (ISP) [The ISP is for further study (see Note 1, Figure 5/Q.700)].
`The TCAP entity is a functional block residing above the ISP in layer 7. TCAP consists of two sub-layers: the
`
`Transaction sub-layer, and the Component sub-layer. Further details are given in Recommendation Q.771.
`
`TC, as currently specified, provides services based on a connectionless network service. In this case, no ISP
`layers 4-6 functions are involved. Connection-oriented TC services, and the layer functions of layers 4-6 are for further
`study.
`
`network.
`TC provides the means to exchange operations and replies via a dialogue. The X.229 Remote Operations
`
`protocol has been extended to provide added functionality in order to accommodate specific user needs. The operations
`and parameters are part of the Application protocol between TC users.
`3.2.3.6 Application Entities and Application Service Elements
`
`In an OSI environment, communication between application processes is modelled by communication between
`“Application Entities (AEs)”. An Application Entity represents the communication functions of an Application process.
`There may be multiple sets of OSI communication functions in an application process, so a single application process
`may be represented by multiple AEs. However, each Application Entity is a set of communication capabilities whose
`components are “Application Service Elements”. An Application Service Element (ASE) is a coherent set of integrated
`functions.
`Application Entities in a CCITT S.S. No. 7 environment
`3.2.3.6.1
`
`Figure 4/Q.700 shows the relationship between Application Processes and Application Entities, and
`Application Service Elements.
`
`An “Application Process” is considered to be a range of functions and features which support a particular
`network requirement. For example, an application process in the context of CCITT S.S. No. 7 provides the co-ordination
`across circuit-related protocols where required.
`
`An Application Process can be considered as:
`a) a co-ordinator of specific aspects of network operation (e.g., ISDN Call Control, Mobiles, OA&M);
`b) an individual service or supplementary service control function (e.g., CUG).
`In the CCITT S.S. No. 7 context, the various functional elements of the signalling system provide the
`
`signalling protocols (information elements, messages, and procedures) necessary to support the service between nodes.
`
`In a CCITT No. 7 environment, Application Entities (AEs) are the elements representing the communication
`functions of the application process, which are pertinent to inter-nodal communication using layer 7 application
`protocols.
`
`The options for the relationship between an application process, AEs and ASEs can take several forms at a
`CCITT No. 7 signalling point. Some examples are shown in Figure 4/Q.700.
`
`
`
`
`
`Fascicle VI.7 – Rec. Q.700
`
`9
`
`Ex. 1017
`YMax Corporation
`Page 11 of 26
`
`

`
`
`
`
`
`is another example of an Application Entity (AE) (see
`
`FIGURE 4/Q.700
`Example of the relationship between the application process, AEs and ASEs
`Application Service Elements in a CCITT No. 7 environment
`3.2.3.6.2
`
`Application Service Elements (ASEs) reside in the CCITT S.S. No. 7 Architecture Model within layer 7 above
`TCAP. In the context of OSI, TCAP could also be considered to be an ASE.
`
`OMAP has an Application Entity currently containing the TCAP ASE and one other ASE. Other ASEs are
`under study. OMAP is described further in § 6.
`
`The Mobile Application Part (MAP)
`Recommendation Q.1051).
`
`An ASE can include a number of signalling procedures for a single service (e.g., Freephone), where this single
`service is the application.
`
`Alternatively, an ASE can include a number of signalling procedures for any number of services or functions,
`encompassed by an application (e.g., MAP, OMAP).
`
`Thus, an ASE can define an individual service protocol (e.g., CUG), or a complete application protocol
`(e.g., MAP).
`
`An ASE can only communicate with a compatible peer ASE. The operations defined in an ASE may be either
`symmetrically invoked by each entity involved in the dialogue, or asymmetrically invoked by one entity only (i.e., on a
`“client/server” basis). An example of the former is a “look ahead if free” procedure; an example of the latter is a database
`enquiry.
`Addressing for Application Entities (AEs)
`3.2.3.6.3
`
`The SCCP provides a mechanism for addressing