1、CCITT RECMNUI.2LO (REV+L) 93 W 4862591 0580487 T34 INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU INTEGRATED SERVICES DIGITAL NETWORK (ISDN) SERVICE CAPABILITIES 1.21 o (03/93) PRINCIPLES OF TELECOMMUNICATION SERVICES SUPPORTED BY AN ISDN AND THE MEANS TO
2、DESCRIBE THEM ITU-T Recommendation 1.21 O (Previously “CCITT Recommendation”) CCITT RECMN*I.ZLO (REVsL) 93 48b259L 0580488 970 FOREWORD The Telecommunication Standardization Sector (-T) is a permanent organ of the International Telecom- munication Union. The -T is responsible for studying technical,
3、 operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Conference (WTSC), which meets every four years, established the topics for study by the ITU-T Study Groups which, in
4、their turn, produce Recommendations on these topics. IT-T Recommendation 1.210 was revised by the -T Study Group XVIII (1988-1993) and was approved by the WTSC (Helsinki, March 1-12, 1993). NOTES 1 As a consequence of a reform process within the International Telecommunication Union (IT), the CCIT c
5、eased to exist as of 28 February 1993. In its place, the Telecommunication Standardization Sector (IT-T) was created as of 1 March 1993. Similarly, in this reform process, the CCIR and the IFRB have been replaced by the Radiocommunication Sector. In order not to deiay publication of this Recommendat
6、ion, no change has been made in the text to references containing the acronyms “CCiT, CCIR or IFRF3” or their associated entities such as Plenary Assembly, Secretariat, etc. Future editions of this Recommendation will contain the proper terminology related to the new ITU structure. 2 telecommunicati
7、on administration and a recognized operating agency. In this Recommendation, the expression “Administration” is used for conciseness to indicate both a O 1993 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, includi
8、ng photocopying and microfilm, without permission in writing from the IT. CONTENTS Page 1 General 1 2 Service concepts . . . . 1 3 Customer access to telecommunication services supported by an ISDN o . 2 4 Capabilities to support a telecommunication service . 3 5.2 Bearer services supported by an IS
9、DN . 5 5 Telecommunication service classification . . . 5.3 Teleservices supported by an ISDN . 6 5.4 Supplementary services supported by an ISDN 8 Provision of telecommunication services . . . . . . . . 9 5 6 Annex A - Structure for prose service definition and description - Step 1.1 of description
10、 method A.l Structure of prose service definition and description A.2 Explanation of the terms and content of the items in the service prose definition and description Annex B - List of attributes and their possible values for describing bearer services - Step 1.2 of description method . . . . . . .
11、 . . . . . . . . ., . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B.1 Framework for the static description of bearer services supported by an ISDN . B.2 List of bearer service attributes Annex C - List of attributes and their possible
12、 values for describing teleservices - Step 1.2 of description method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C.1 Framework for the siatic description of teleservices supported by an ISDN C.2 List of the teleservice attribu
13、tes . C.3 List of the service component attributes . Annex D - Dynamic description of the service using graphic means - Step 1.3 of description method . D.l Introduction D.2 Over amended at Melbourne, 1988 and at Helsinki, 1993) 1 General An ISDN will support a wide range of services as described ge
14、nerally in Recommendation 1.120. The purpose of this Recommendation is to provide a classification of such services, the means for the description of such services based on the description method as defined in Recommendation 1.130, and to give a basis for the definition of the network capabilities r
15、equired by an ISDN. These network capabilities are defined in the 1.300-Series Recommendations. Using the service concepts and the means for the description of services as given in this Recommendation, recommended bearer services are defined and described in the 1.230-Series Recommendations, recomme
16、nded teleservices are defined and described in the 1.240-Series Recommendations and recommended supplementary services are defined and described in the 1.250-Series Recommendations. 2 Service concepts 2.1 Services supported by an ISDN are the communication capabilities made available to customers by
17、 telecommunication service providers. An ISDN will provide a set of network capabilities which are defined by standardized protocols and functions and enable telecommunication services to be offered to customers. A service provision by a telecommunication service provider to a customer connected to
18、an ISDN may cover the whole or only part of the means required to fully support the service. The operational and commercial features associated with provision of the service are included in the service concept The service classification and descriptions which follow are independent of different poss
19、ible arrangements for ownership and provision to the customer of the means required to support a service. The customer may therefore be offered, by the Adminisiration, services or service support. 2.2 The method used for the characterization of telecommunication services is described in Recommendati
20、on 1.130 “Method for the characterization of telecommunication services supported by an ISDN and network capabilities of an ISDN”. Within this method the first stage is an overall service description from the users point of view. In stage 1 there are three steps: Step 1.1 : Prose service definition
21、and description; Step 1.2 Static description of the service using attributes; Step 1.3: Dynamic description of the service using graphic means. Together these three steps define the service characteristics as they apply at a given reference point where the customer accesses the service. Annexes A to
22、 D give the format of stage 1 service descriptions as follows: - Annex A Structure for prose service definition and description; - - - NOTES 1 2 Annex B: List of attributes and their possible values for describing bearer services; Annex C: List of attributes and their possible values for describing
23、teleservices; Annex D: Dynamic description of the service using graphic means. Recommendation 1.140 describes the use of attributes for this purpose. The use of attributes for describing supplementary services is for further study. This format allows the information contained within stage 1 to be st
24、ructured in a consistent, comprehensive and logical manner. Only one overall format is recommended but it is recognized that certain sections of this format are only applicable to certain types of services. Recommendation 1.210 (03/93) 1 CCITT RECNN*I-210 (REV*L) 93 4862591, 058049L 465 D Bearer ser
25、vice Basic bearer service Basic bearer service + supplementary services 2.3 this Recommendation (except Annexes A and D) deais mainly with step 1.2 of the dwption method. A telecommunication service is, from the static point of view, composed of Telecommunication services are classified using their
26、static characte and - teleservices. A supplementary service modifies or supplements a basic telecommunication service. Consequently, it cannot be offered to a customer as a stand alone service. It must be offered together with or in association with a basic telecommunication service. The same supple
27、mentary service may be common to a number of telecommunication services. NOTE - The concept of supplementary services corresponds to the concept of optional user facilities in the X-Series Recommendations. Teleservice Basic teleservice Basic teleservice + supplementary services The concepts introduc
28、ed here are illustrated in Table 1 and are defmed in more detail in 5. TABLE 1D.210 Classification of telecommunication services I Telecommunication service I 3 Customer access to telecommunication services supported by an ISDN 3.1 Considering the reference configurations defined in Recommendation 1
29、.411, customers can access various telecommunication services at different access points. Figure 1 shows these access points. This figure takes into account the fact that the network provider may offer to a customer connected to an ISDN the whole or only part of the means to fully support the servic
30、e. TE1 I NT2 r NT1 S T ) TI 20380-WdOl FIGURE 1D.210 customer access to services supported by an ISDN 2 Recommendation 1.210 (03/93) CCITT RECMN*I.ZLO (REVML) 93 W 48b259L 0580472 3TL 3.2 The definitions of the access points introduced in Figure 1 are as follows: i) Access points 1 (reference point
31、T) and 2 (reference point S) are the access points for bearer services supported by an ISDN. The choice between access point 1 (T) and 2 (S) depends on the ownership and form of provision (to the customer) of the communications equipment at the customer premises. The service classification and descr
32、iptions in the following are independent of different possible arrangements for such provision. ii) At access point 4 (reference point R), depending on the type of terminal adaptors provided, other CCIIT standardized services may be accessed, e.g. according to the X- and V-Series Recommendations. ii
33、i) At access points 3 and 5 (user-to-tenninal interface), teleservices are accessed - the teleservice concept includes the terminai capabilities. 3.3 The following customer entities may be connected at access points 1 and 2: - customer terminais; - customer systems, e.g. PABXs, LANs, service vendor
34、systems; - private networks. NOTE - Customer terminais and systems may be private or provided by Administrations. Ail customer equipment connected rn an ISDN interface at one of these access points should meet the specifications of the protocols at that interface for ail the layers that are included
35、 in the definition of the telecommunication service used. For some telecommunication services the service definition also covers some terminal functions and characteristics in addition to those specified by the protocols at the interface. This relates in particular to .teleservices, and also to supp
36、lementary services (see Recommendation 1.250). 3.4 From the users point of view the telecommunication services as defined in the 1.200-Series Recommendations will be used for some applications. For example, the telephony teleservice will be typically used for a human conversation (application). Like
37、wise bearer services will be used for applications. The area of applications is outside the scope of the I-Series Recommendations. The users application of services is the responsibility of the user and not of the network. The network can have no knowledge of what application is being used at any gi
38、ven time. 3.5 The telecommunication service, as described in this Recommendation, is time-independent, that is to say that the description is valid for all the time the service is available. Whenever a demand or reserved service is invoked by a user, then the particular instance of the service is re
39、ferred to as a call. Similarly, the instance also applies to the application as described in 3.4. The instance of an application is referred to as a communication. 4 Capabilities to support a telecommunication service 4.1 include: The capabilities required to fully support a telecommunication servic
40、e for a customer connected to an ISDN - network capabilities; - terminal capabilities, when required; - - other services providing capabilities, when required; operational and commercial features associated with the service provision (i.e. sales or marketing aspects). 4.2 capabilities are introduced
41、 in that Recommendation: Network capabilities are described in detail in Recommendation 1.310. Two different levels of ISDN network - low layer capabilities which relate to bearer services; - high layer capabilities which together with low layer capabilities relate to teleservices. Recommendation 1.
42、210 (03/93) 3 CCITT RECNN*I*ZLO (REV* - additional low layer functions (ALLF) supporting, in addition to BLLFs, lower layer requirements of supplementary services. High layer capabilities are defined as a set of high layer functions (HLF) generally associated with layers 4 to 7 in Recommendation X.2
43、00. High layer functions are subdivided into basic high layer functions (BHLF) and additional high layer functions (AHLF). NOTE - Depending on national regulations, ALLE BHLF, and AHLF may be provided by administrations, or other suppliers. 4.3 The concept of describing network capabilities in terms
44、 of low layer capabilities and high layer capabilities can equally be applied to describe terminal capabilities. In the description of teleservices the HLF and LLF are included in the service definition. In the case of bearer service definition the terminal capabilities are not included but the term
45、inal must conform to the LLF of the bearer service. NOTE - The relationships between service categories, network/terminal capabilities and functions are illustrated in Table 2. TABLE uI.210 Relationship between service categories, network/terminal capabilities and functions Network capabilities spec
46、ified Terminal capabilities specified Depending on national regulations, ALLF, BHLF and AHLF may be provided by administrations or other suppliers. X Specified - Notspecified Commercial Telecom- vlpiF I LLF I HLF I munication service featured Operational BLLF AUP) BHLP) AIUP) BLLF ALLF BHLF AIUF Bea
47、rer service X Optional - X Teleservice X Optional Optional Optional X Optional X Optional X 4.4 maintenance, charging, user control of service features, etc. The operational service capabilities associated with a service offering may include capabilities for The use of such capabilities may involve
48、terminal-network communication and may therefore be viewed as specific appiications. A more precise description of these capabilities and the relationship to Remmendation X.200 needs further study. 4 Recommendation I210 (03/93) CCITT RECflN*I.2LO (REV* - high layer attributes. Bearer services are de
49、fined as including only low layer attributes. Teleservices are defined as including both low layer attributes and high layer attributes. The relationship between telecommunication service attributes and lowhigh layer functions is illustrated in Figure 2. Service attribu tes Telecommunication seNiCe (Teleservice (Teleservice only) oniy) Basic service attributes Supplementary services attributes (Note 1) functions in network or layer functions layer functions layer functions layer functions teminal TI 820390-93/602 NOTES 1 A supplementary service cannot be offere
