ANSI ATIS 1000631-2005 Signaling System No 7 (SS7) C High Probability of Completion (HPC) Network Capability.pdf

1、 AMERICAN NATIONAL STANDARD FOR TELECOMMUNICATIONS ATIS-1000631.2005(R2015) Signalling System No. 7 (SS7) High Probability of Completion (HPC) Network Capability As a leading technology and solutions development organization, ATIS brings together the top global ICT companies to advance the industrys

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5、TEL). For more information, visit . AMERICAN NATIONAL STANDARD Approval of an American National Standard requires review by ANSI that the requirements for due process, consensus, and other criteria for approval have been met by the standards developer. Consensus is established when, in the judgment

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10、the American National Standards Institute require that action be taken periodically to reaffirm, revise, or withdraw this standard. Purchasers of American National Standards may receive current information on all standards by calling or writing the American National Standards Institute. Notice of Di

11、sclaimer Special marking of each set-up message by each network exchange to increase the probability of it being transferred to the next exchange in the case of congestion in the signaling network. This standard only describes the transfer of the indicator through an ISDN and the signaling interwork

12、ing with non-ISDNs. This network capability may be utilized by standardized or non-standardized services accessible to either ISDN or non-ISDN subscribers. 2 NORMATIVE REFERENCES The following standards contain provisions which, through reference in this text, constitute provisions of this American

13、National Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this American National Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated be

14、low. ATIS-1000631.2005 2 T1.111-1992, Signaling system no. 7 (SS7) Message transfer part (MTP).1T1.113-1992, Signaling system no. 7 (SS7) Integrated services digital network (ISDN) User part. 1T1.401-1988, Interface between carriers and customer installations Analog voicegrade switched access lines

15、using loop-start and ground-start signaling. 1T1.609-1990, Interworking between the ISDN usernetwork interface protocol and the signaling system number 7 ISDN user part. 1T1.615-1992, Digital subscriber signaling system no.1 (DSS1) Layer 3 overview. 13 GENERAL DESCRIPTION The configurations of netwo

16、rk entities described in this standard are depicted in Figure 1. The network entities and signaling interfaces shown with dashed lines are included for reference only and are not specified in this standard. The network and user equipment configurations shown are based on the “functional groupings” d

17、efined in T1.615 and applicable CCITT Recommendations on ISDN. Although these functional groupings may correspond to actual physical entities, actual implementations may incorporate more than one of these functional groupings in a single physical entity or may provide a subset of one or more of thes

18、e functional groupings. A summary of the functional groupings as used in this standard is as follows: Local Exchange (LE). In the configurations, this is the switch in the public network to which “users” are connected; Transit Exchange (TR). In the configurations, this is a switch in the public netw

19、ork that provides connections between two Local Exchanges; Signaling Transfer Point (STP). In the configurations, this is the switch that transfers the Signaling System 7 call set-up messages between LEs and TRs. For each message transfer, it may represent one or more sequential STPs. 3.1 Operation

20、at originating exchange The originating Local Exchange shall determine the need to mark a call set-up with the special NS/EP indicator; however, the method used is not covered by this standard, but could be provided by future standards. For example, it may perform this function by recognition of one

21、 or a combination of the following: A special access code such as *XXX preceding the dialed called party number; Call origination from a specially marked line; Recognition of a call to a unique called party number or range of numbers such as 710-950-XXXX; Administrative actions to activate the servi

22、ce for a period of time. The originating exchange shall perform the following two procedures: 1This document is available from the Alliance for Telecommunications Industry Solutions, 1200 G Street N.W., Suite 500, Washington, DC 20005. ATIS-1000631.2005 3 The special NS/EP indicator described in 4.1

23、.1.1 shall be included in the outgoing SS7 ISUP IAM message used to set-up the call; The outgoing IAM message shall be marked with a Congestion Priority Level of 1 (unless the operation of some other service has already resulted in its marking at a higher level). In the case of congestions in the si

24、gnaling network, this will prevent this message from being discarded until after all lower-priority messages have been discarded, in accordance with the procedures of T1.111. 3.2 Operation at the Transit Exchange The Transit Exchange shall recognize the need for special handling by detection of the

25、special NS/EP indicator in its received call set-up message (IAM). A service, not included in this standard, at the Transit Exchange may determine the need to mark a call set-up message with the NS/EP indicator, for example, by the called party number method described in 3.1. The Transit Exchange sh

26、all perform the same procedures as described for the originating exchange above. 3.3 Operation at the Terminating Exchange The Terminating Exchange shall recognize the need for special handling by detection of the special NS/EP indicator in its received call set-up message (IAM). The Terminating Exc

27、hange shall perform the following functions: It shall route the call to the destination user via its normal processing; Further processing, such as return of answer, cut-through of the speech path, and release shall be performed as described in other applicable American National Standards (T1.113 an

28、d T1.609). 3.4 Operation at an interworking exchange (non-ISDN to ISDN) In the case of a call entering the ISDN via a non-ISDN signaling system at an interworking exchange (TR in configuration (b) of Figure 1), the operation depends on the capability of that non-ISDN signaling system. The ISDN Inter

29、working Exchange shall recognize the need to mark a call set-up with the special NS/EP indicator; however, that method is not covered by this standard. For example, it may perform this function by recognition of one or a combination of the following: Recognition of the called party number being a un

30、ique number or within a range of numbers such as 710-950-XXXX; Administrative actions to activate the service for a period of time. The non-ISDN to ISDN interworking exchange shall perform the same functions as described above for the originating exchange. 3.5 Operation at an interworking exchange (

31、ISDN to non-ISDN) In the case of a call encountering interworking from the ISDN to a non-ISDN signaling system to another exchange (TR in configuration (c) of Figure 1), the call over the non-ISDN signaling system proceeds as a non-NS/EP call. ATIS-1000631.2005 4 3.6 Operation at the STP The STP sha

32、ll not recognize the special marking of the call set-up (IAM) as an NS/EP call. However, in accordance with T1.111, the STP shall maintain the Congestion Priority when it transfers a call set-up message to the destination exchange (or to the next STP). 3.7 Operation at a domestic gateway exchange In

33、 the case of a United States exchange performing a gateway function with another United States network, the gateway exchange shall continue a call with a Calling Partys Category (CPC) of “NS/EP call”. The outgoing IAM shall be marked with a MTP message priority level of 1. 3.8 Operation at an intern

34、ational gateway exchange If an international gateway exchange sends to or receives from another countrys ANSI SS7 network a call with the CPC coded as “NS/EP call”, the CPC coding shall be changed to “calling partys category unknown”2. If an international gateway exchange receives a call from an ITU

35、-T SS7 network with the CPC set to “International Emergency Preference Scheme” (IEPS), the CPC coding shall be changed to “ordinary calling subscriber”3. 4 SWITCHING AND SIGNALING SPECIFICATIONS FOR HPC 4.1 Formats and coding The functional description, formats and codes, and general procedures for

36、the ISDN User Part are contained in T1.113. 4.1.1 ISDN-User Part formats and parameter codings The IAM purpose, format, and coding are specified in T1.113. The relevant parameter is the Calling Partys Category parameter: The Calling Partys Category parameter in the IAM for an HPC call will use the “

37、National Security and Emergency Preparedness (NS/EP) call” codepoint 11100010. 4.2 Procedures Normal call control procedures according to T1.113 apply. NS/EP end user procedures or services may also be available at selected exchanges. The flow diagram for a successful call is shown in Figure 2. 2A p

38、olicy or mutual agreement may exist between the United States and the other country to allow call establishment with priority treatment. In this case, the call is progressed with the CPC coded as “NS/EP call” in the IAM. The IAM shall be marked with a MTP message priority level of 1. 3A policy or mu

39、tual agreement may exist between the United States and the other country to allow call establishment with priority treatment. In this case, the call is progressed with the CPC coded as “NS/EP call” in the outgoing IAM. The outgoing IAM shall be marked with a MTP message priority level of 1. ATIS-100

40、0631.2005 5 4.2.1 Successful call set-up When the originating exchange has received complete call information from the calling party, and has determined that the call is to be routed to another exchange, the selection of a suitable, free, interexchange circuit takes place and an Initial Address Mess

41、age is sent to the succeeding exchange. Appropriate routing information is either stored at the originating exchange or at a remote database to which a request may be made. If the call is recognized as an NS/EP call, the NS/EP call code will be set in the Calling Partys Category parameter of the Ini

42、tial Address Message. The originating exchange shall determine the need to mark a call set-up with the special NS/EP indicator, however, the method used is not covered by this standard. For example, it may perform this function as described in 3.1. The Initial Address Message will be sent to the suc

43、ceeding exchange using a message priority level of 1. As in a normal call, an intermediate ex-change, on receipt of an Initial Address Message, shall analyze the called party number, the Protocol Control Indicator, the ISDN User Part Preference Indicator, the bearer capability specified in the User

44、Service Information parameter, and any other routing information to determine the routing of the call. An NS/EP call shall be recognized by the intermediate exchange by identification of the NS/EP call code in the Calling Partys Category parameter of the Initial Address Message. The Initial Address

45、Message for an NS/EP call will be sent to the succeeding exchange using a message priority level of 1. There are no special procedures at the destination exchange. 4.3 HPC messages priority assignment The HPC IAMs will be sent at message priority level 1 to allow a higher probability of successful c

46、all initiation during periods of network congestion. ATIS-1000631.2005 Figure 1: Configuration of equipment of the HPC network capability 6 ATIS-1000631.2005 Calling Party Terminating Exchange Called Party Transit ExchangeOriginating Exchange ACM IAM (NS/EP identifier + priority) ACM ANM ANM AlertAn

47、swerNS/EP Call Request IAM (NS/EP identifier + priority) Figure 2: Normal HPC Call Set-Up 7 ATIS-1000631.2005 8 Annex A (informative) ANNEX A NS/EP TELECOMMUNICATIONS SERVICE CALL EXAMPLES Examples of the possible operation of NS/EP Telecommunications service calls are described in the following cla

48、use to provide information. It is not the intent of this clause to standardize the operation of these services but rather to provide examples of services that might make use of the HPC network capability. A.1 Example 1 This example shows a call that is similar to an 800 service with interactive feat

49、ures. In this example, the higher-level NS/EP functions such as user authentication are provided by a transit exchange. The call flow diagram for this call is shown in Figure A.1. In this example, the calling party goes off-hook and dials a 10-digit number that indicates that the caller wishes to place an NS/EP call. This number is not the called party number but is rather an access number for the NS/EP service. The originating exchange recognizes this call as an NS/EP call based on 6-digit translation and assembles an IAM that