S tandard ECMA-213
3rd Edition - December 2001
Standardizing Information
and
Communication
Systems
Private Integrated Services Network (PISN) Specification, Functional Model and Information Flows Recall Supplementary Service
Phone: +41 22 849.60.00 - Fax: +41 22 849.60.01 - URL: http://www.ecma.ch - Internet: [email protected]
.
S tandard ECMA-213
3rd Edition - December 2001
Standardizing
Information
and
Communication
Systems
Private Integrated Services Network (PISN) Specification, Functional Model and Information Flows Recall Supplementary Service (RESD)
Phone: +41 22 849.60.00 - Fax: +41 22 849.60.01 - URL: http://www.ecma.ch - Internet: [email protected] IW
Ecma-213.doc
14-01-02 15,44
.
Brief History
This Standard is one of a series of ECMA Standards defining services and signalling protocols applicable to Private Integrated Services Networks (PISNs). The series uses ISDN concepts as developed by ITU-T and conforms to the framework of International Standards for Open Systems Interconnection as defined by ISO/IEC. This particular Standard specifies the Recall supplementary service. This Standard is based upon the practical experience of ECMA member companies and the results of their active and continuous participation in the work of ISO/IEC JTC1, ITU-T, ETSI and other international and national standardization bodies. It represents a pragmatic and widely based consensus. Compared to the 1st Edition of Standard ECMA-213 (published by ECMA in December 1994), the 2nd Edition (published by ECMA in June 1997) incorporated changes in order to achieve complete alignment with International Standard ISO/IEC 15051:1997(E) published by ISO/IEC in May 1997.
Adopted as 3rd Edition of Standard ECMA-213 by the General Assembly of December 2001.
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Table of contents 1
Scope
1
2
Conformance
1
3
References (normative)
1
Definitions E x te r n a l d e f in itio n s
1 1
4.2 Other definitions 4.2.1 Bu sy 4.2.2 Call, basic call 4.2.3 Recall busy 4.2.4 R e c a l l b u s y t i me r 4.2.5 Recall no answer 4.2.6 R e c a l l n o a n s w e r t i me r 4.2.7 Served user 4.2.8 W a itin g a t b u s y u s e r
2 2 2 2 3 3 3 3 3
5
3
4 4.1
6
List of acronyms S S - R E s t a g e 1 s p e c if ic a t io n 6 . 1 D e s c r ip tio n 6.1.1 G e n e r a l d e s c r ip tio n 6.1.2 Q u a l i f i c a t i o n s o n a p p l i c a b i l i t y t o t e l e c o mmu n ic a t i o n s e r v i c e s 6.2 Procedures 6.2.1 P r o v is io n /w ith d r a w a l 6.2.2 N o r ma l p r o c e d u r e s 6.2.3 E x c e p tio n a l p r o c e d u r e s 6 . 3 I n te r a c tio n s w ith o th e r s u p p le me n ta r y s e r v ic e s a n d A N F s 6.3.1 Calling line identification presentation (SS-CLIP) 6.3.2 C o n n e c t e d l i n e i d e n t i f i c a t io n p r e s e n ta tio n ( S S - CO L P ) 6.3.3 C a l l i n g /c o n n e c t e d l i n e i d e n t i f i c a t i o n r e s t r i c t i o n ( S S - C L I R ) 6.3.4 C a l l i n g n a me i d e n t i f i c a t i o n p r e s e n t a t i o n ( S S - C N I P ) 6.3.5 C o n n e c t e d n a me i d e n t i f i c a t io n p r e s e n ta tio n ( S S - CO N P ) 6.3.6 Ca llin g /c o n n e c te d n a me id e n tif ic a tio n r e s tr ic tio n ( S S - CN I R) 6.3.7 Ca ll f o r w a r d in g u n c o n d itio n a l ( S S - CF U ) a n d Ca ll d e f le c tio n imme d ia te ( S S - CD I ) 6.3.8 Ca ll f o r w a r d in g b u s y ( S S - CF B) 6.3.9 Ca ll f o r w a r d in g n o r e p ly ( S S - CF N R) a n d Ca ll d e f le c tio n f r o m a le r tin g ( S S - CD A ) 6.3.10 Do-not-disturb (SS-DND) 6.3.11 Do-not-disturb override (SS-DNDO) 6.3.12 C a l l c o mp l e t i o n t o b u s y s u b s c r i b e r ( S S - C C B S ) 6.3.13 Ca ll c o mp le tio n o n n o r e p ly ( S S - CCN R) 6.3.14 Call offer (SS-CO)
3 3 3 3 4 4 4 4 5 5 5 5 5 5 5 5 5 5 5 5 5 5 6
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7
6.3.15 Call transfer (SS-CT) 6.3.16 P a t h r e p l a c e me n t ( A N F - P R ) 6.3.17 Call intrusion (SS-CI) 6.3.18 Advice of charge (SS-AOC) 6.3.19 Call interception (ANF-CINT) 6 . 4 I n te r w o r k in g c o n s id e r a tio n s 6.5 Overall SDL
6 6 6 6 6 6 6
S S - R E s t a g e 2 s p e c if ic a t io n 7 . 1 F u n c tio n a l mo d e l 7.1.1 F u n c tio n a l mo d e l d e s c r ip tio n 7.1.2 Description of functional entities 7.1.3 Re la tio n s h ip o f f u n c tio n a l mo d e l to b a s ic c a ll f u n c tio n a l mo d e l 7 . 2 I n f o r ma t i o n f l o w s 7.2.1 D e f in itio n o f in f o r ma tio n f lo w s 7.2.2 Re la tio n s h ip o f in f o r ma tio n f lo w s to Ba s ic Ca ll in f o r ma tio n f lo w s 7.2.3 E x a mp le o f in f o r ma tio n f lo w s e q u e n c e s 7.3 Functional entity actions 7.3.1 Functional entity actions of FE1 7.3.2 Functional entity actions of FE2 7.3.3 Functional entity actions of FE3 7.3.4 Functional entity actions of FE4 7 . 4 F u n c t i o n a l e n t i t y b e h a v io u r 7.4.1 Be h a v io u r o f F E 1 7.4.2 Be h a v io u r o f F E 2 7.4.3 Be h a v io u r o f F E 3 7.4.4 Be h a v io u r o f F E 4 7 . 5 A l l o c a t i o n o f f u n c t i o n a l e n t i t i e s t o p h ys i c a l e q u ip me n t
8 8 8 8 8 9 9 9 10 10 10 10 11 11 11 11 11 13 13 14
1
Scope This Standard specifies supplementary service Recall (SS-RE), which is applicable to various basic services supported by Private Integrated Services Networks (PISN). Basic services are specified in ECMA-142. SS-RE is a supplementary service which provides for the redirection of a call transferred by the served user back to the served user if the call is unanswered. SS-RE is only applicable after transfer by join, not after transfer by rerouteing. Service specifications are produced in three stages, according to the method described in ETS 300 387. This Standard contains the stage 1 and stage 2 specifications of SS-RE. The stage 1 specification (clause 6) specifies the supplementary service as seen by users of PISNs. The stage 2 specification (clause 7) identifies the functional entities involved in the supplementary service and the information flows between them.
2
Conformance In order to conform to this Standard, a Stage 3 standard shall specify signalling protocols and equipment behaviour that are capable of being used in a PISN which supports the supplementary service specified in this Standard. This means that, to claim conformance, a Stage 3 standard is required to be adequate for the support of those aspects of clause 6 (stage 1) and clause 7 (stage 2) which are relevant to the interface or equipment to which the Stage 3 standard applies.
3
References (normative) The following standards contain provisions which, through reference in this text, constitute provisions of this Standard. All standards are subject to revision, and parties to agreements based on this Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. In the case of references to ECMA Standards that are aligned with ISO/IEC International Standards, the number of the appropriate ISO/IEC International Standard is given in brackets after the ECMA reference. ECMA-133
Private Integrated Services Network (PISN) - Reference Configuration for PISN Exchanges (PINX) (International Standard ISO/IEC 11579-1)
ECMA-142
Private Integrated Services Network (PISN) - Circuit-mode 64 kbit/s Bearer Services Service Description, Functional Capabilities and Information Flows (International Standard ISO/IEC 11574)
ECMA-177
Private Integrated Services Network (PISN) - Specification, Functional Model and Information Flows - Call Transfer Supplementary Service (International Standard ISO/IEC 13865)
ETS 300 387
Private Telecommunication Network (PTN); Method for the specification of basic and supplementary services (1994)
ITU-T Rec. I.112
Vocabulary of terms for ISDNs (1993)
ITU-T Rec. I.210
Principles of telecommunication services supported by an ISDN and the means to describe them (1993)
ITU-T Rec. I.221
Common specific characteristics of services (1993)
ITU-T Rec. Z.100 Specification and description language (1999)
4
Definitions For the purposes of this Standard, the following definitions apply.
4.1
External definitions This Standard uses the following terms defined in other documents: − Basic Service
(ITU-T Rec. I.210)
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− Connection
(ITU-T Rec. I.112)
− Network Determined User Busy
(ITU-T Rec. I.221)
− Primary Call
(ECMA-177)
− Private Integrated Services Network (PISN)
(ECMA-133)
− Private Integrated services Network eXchange (PINX)
(ECMA-133)
− Secondary Call
(ECMA-177)
− Service
(ITU-T Rec. I.112)
− Signalling
(ITU-T Rec. I.112)
− Supplementary Service
(ITU-T Rec. I.210)
− User
(ECMA-142)
− User A
(ECMA-177)
− User B
(ECMA-177)
− User C
(ECMA-177)
− User Determined User Busy
(ITU-T Rec. I.221)
This Standard refers to the following basic call functional entities (FEs) defined in ECMA-142: − Call Control (CC) − Call Control Agent (CCA) This Standard refers to the following basic call inter-FE relationships defined in ECMA-142: − r1 − r2 − r3 This Standard refers to the following basic call information flows defined in ECMA-142: − Report request/indication − Setup request/indication − Setup response/confirmation This Standard refers to the following basic call information flow elements defined in ECMA-142: − Connected Number (CN) − Connected Subaddress (CS)
4.2
Other definitions
4.2.1
Bu s y A property of a user for whom either a Network Determined User Busy or a User Determined User Busy condition exists.
4.2.2
C a ll, b a s ic c a ll An instance of the use of a basic service.
4.2.3
R e c a ll b u s y The redirection of a transferred call back to the served user if the call is waiting at a busy user C and user C remains busy.
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4.2.4
Recall busy timer A timer governing the period that a transferred call will wait at a busy user C before Recall busy occurs. The value of this timer is implementation specific.
4.2.5
R e c a ll n o a n s we r The redirection of a transferred call back to the served user if user C is being alerted and does not answer.
4.2.6
Recall no answer timer A timer governing the period that a transferred call will alert user C before Recall no answer occurs. The value of this timer is implementation specific.
4.2.7
Served user A User A that is provided with SS-RE.
4.2.8
W a it in g a t b u s y u s e r A call state in which a call is awaiting answer at a user that is busy on another call. NOTE This can arise, for example, as a result of the use of supplementary service Call Offer (SS-CO) during call establishment. A call that is waiting on busy can be transferred.
5
List of acronyms
6
ANF
Additional Network Feature
CC
Call Control (functional entity)
CCA
Call Control Agent (functional entity)
CN
Connected Number
CS
Connected Subaddress
DC
Destination Category
FE
Functional Entity
ISDN
Integrated Services Digital Network
PINX
Private Integrated services Network eXchange
PISN
Private Integrated Services Network
SDL
Specification and Description Language
SS-RE
Supplementary Service Recall
TE
Terminal Equipment
SS-RE stage 1 specification
6.1 6.1.1
Description General description When the served user has a call established with user B and transfers that call to user C, SS-RE enables user B to be re-connected to the served user either if user C is being alerted and does not reply within a specified period (recall no answer), or if the call is waiting at busy user C and user C remains busy for a specified period (recall busy). An implementation may provide either of these variants or both. NOTE If the served user fails to respond to the incoming re-directed call, the call may be cleared or subjected to other action which is beyond the scope of this specification.
6.1.2
Qualifications on applicability to telecommunication services SS-RE is applicable to all basic services defined in ECMA-142.
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6.2
Procedures
6.2.1
P r o v is io n /wit h d r a wa l SS-RE may be provided after pre-arrangement with the service provider, or may be available generally to all users. SS-RE may be withdrawn on request of the user or for administrative reasons. The subscription parameters and values offered by a PISN shall be an implementation matter. A PISN may offer more or less parameters and values than those specified below. Table 1 - SS-RE Subscription parameters Subscription option
Value
Recall no answer
select or de-select
Recall busy
select or de-select
6.2.2 Normal procedures 6.2.2.1 A c t iv a t io n /d e a c t iv a t io n /r e g is t r a t io n /in t e r r o g a t io n Not applicable. 6.2.2.2
I n v o c a t io n a n d o p e r a t io n SS-RE may be invoked by the PISN on behalf of the served user in conjunction with a call transfer, if the secondary call is not in the active state. NOTE The invocation of SS-RE may be dependent upon call type and/or other factors that are beyond the scope of this Standard. If the secondary call is waiting at busy user C at the time of call transfer and if Recall busy is applicable, then the recall busy timer shall be started. If user C becomes not busy and starts to be alerted before the recall busy timer expires, Recall busy shall be cancelled. If user C is being alerted at the time of call transfer, or was busy and subsequently starts to be alerted, and if Recall no answer is applicable, then the recall no answer timer shall be started. For both Recall busy and Recall no answer, if user C answers within the recall timer limit SS-RE shall be cancelled. If the recall busy timer expires before user C accepts the call or starts to be alerted, or the recall no answer timer expires before user C accepts the call, then the primary call shall be redirected to the served user, and user B's connection with user C shall be cleared either immediately or when the served user starts to be alerted. The served user shall receive a notification that recall takes place, together with the recall reason plus the identity of user C, if available and presentation is not restricted. If user C's number is not available or its presentation is restricted, the original called number of the secondary call shall be indicated instead. User B shall be notified when recall takes place and, if the served user is being alerted, also when the served user answers; the notification shall include the served user's identity, unless presentation is restricted and user B has no override capability.
6.2.3 Ex c e p t io n a l p r o c e d u r e s 6.2.3.1 A c t iv a t io n /d e a c t iv a t io n /r e g is t r a t io n /in t e r r o g a t io n Not applicable. 6.2.3.2
I n v o c a t io n a n d o p e r a t io n If the redirection of the primary call fails, e.g. because the served user is busy, the transferred call may continue waiting at user C or alerting user C, whichever is applicable. If it does not continue, or if the served user does not answer the incoming redirected call, additional means to complete the call may be provided as an implementation option.
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NOTE These additional means are beyond the scope of this Standard.
6.3
Interactions with other supplementary services and ANFs Interactions with other supplementary services and ANFs for which PISN standards were available at the time of publication of this Standard are specified below.
6.3.1
Calling line identification presentation (SS-CLIP) When recall busy or no answer takes place user B's identity shall be presented to the served user by means of SS-CLIP, provided no restriction applies.
6.3.2
Connected line identification presentation (SS-COLP) No interaction.
6.3.3
C a l l i n g /c o n n e c t e d l i n e i d e n t i f i c a t i o n r e s t r i c t i o n ( S S - C L I R ) If SS-CLIR applies to any of the involved users' number this number shall not be presented in the context of SS-RE, unless the receiving user has override capability.
6.3.4
Calling name identification presentation (SS-CNIP) When recall busy or no answer takes place user B's name shall, if available, be presented to the served user by means of SS-CNIP, provided no restriction applies.
6.3.5
Connected name identification presentation (SS-CONP) No interaction.
6.3.6
C a l l i n g /c o n n e c t e d n a m e i d e n t i f i c a t i o n r e s t r i c t i o n ( S S - C N I R ) If SS-CNIR applies to user B's name this name shall not be presented in the context of SS-RE, unless the served user has override capability.
6.3.7
C a l l f o r w a r d i n g u n c o n d it i o n a l ( S S - C F U ) a n d C a l l d e f l e c t i o n i m m e d i a t e ( S S - C D I ) No interaction if SS-CFU or SS-CDI is invoked at user C. SS-RE may override SS-CFU if activated at the served user. If SS-RE does not override SS-CFU then no SS-CFU information shall be indicated to the calling user (user B). No interaction if SS-CDI is invoked at the served user.
6.3.8
C a ll f o r wa r d in g b u s y ( S S - C F B) No interaction if SS-CFB is activated at user C. SS-RE may override SS-CFB if activated at the served user. If SS-RE does not override SS-CFB then no SS-CFB information shall be indicated to the calling user (user B).
6.3.9
C a l l f o r wa r d i n g n o r e p l y ( S S - C F N R ) a n d C a l l d e f l e c t i o n f r o m a l e r t i n g ( S S - C D A ) If SS-CFNR or SS-CDA is invoked at user C, SS-RE shall be cancelled. SS-RE may be re-invoked against the new user C (i.e. the diverted-to user). No interaction if SS-CFNR or SS-CDA is invoked at the served user.
6.3.10
Do-not-disturb (SS-DND) SS-RE may override SS-DND, if active at the served user.
6.3.11
Do-not-disturb override (SS-DNDO) No interaction.
6.3.12
C a ll c o m p le t io n t o b u s y s u b s c r ib e r ( S S - C C BS ) No interaction.
6.3.13
Call completion on no reply (SS-CCNR) No interaction.
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6.3.14
C a ll o f f e r ( S S - C O ) A call transfer occurring after successful invocation of SS-CO on the secondary call and before completion of SS-CO may lead to the invocation of SS-RE (recall busy).
6.3.15
C a ll t r a n s f e r ( S S - C T) This interaction is specified in 6.2.2.2 and 6.2.3.2.
6.3.16
Path replacement (ANF-PR) No interaction.
6.3.17
C a ll in t r u s io n ( S S - C I ) A call transfer occurring after reaching the Call-Intrusion-Wait-On-Busy state on the secondary call, but before completion of SS-CI, may lead to the invocation of SS-RE (recall busy).
6.3.18
A d v ic e o f c h a r g e ( S S - A O C ) No interaction.
6.3.19
Call interception (ANF-CINT) A call redirected as a result of SS-RE may be subject to interception. NOTE ANF-CINT can be used instead of SS-RE, e.g. in case of transfer by rerouteing.
6.4
Interworking considerations The operation of SS-RE is independent of the location of user C, however, due to interworking the number of user C may not be available when notifying user A of the occurrence of recall. In that case the original called number of the secondary call shall be presented. SS-RE can be provided to user A also in the case that user B is in another network. The PISN shall send any notifications associated with recall to the other network if that network is capable of receiving them. If user B is in the PISN and the PISN receives notifications from another network that provides a service similar to SS-RE, the notifications shall be passed on to user B.
6.5
Overall SDL Figure 1 contains the dynamic description of SS-RE using the Specification and Description Language (SDL) defined in ITU-T Rec. Z.100. The SDL process represents the behaviour of the network in providing SS-RE. The relationship of this process to the basic call process is indicated in the annotations. Output signals to the left represent primitives to user A. Input signals from the right represent inputs from the basic call process, or inputs from an internal process. Output signals to the right represent primitives to user B.
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ID L E T ra n s fe r h a s o c c u rre d o r a tr a n s f e r r e d c a l l h a s s ta rt e d to a l e r t u s e r C a f te r a p e r i o d o f w a i t- o n - b u s y In itia te S S -R E
s e t a p p ro p ria te re c a ll tim e r
re c a ll p e n d in g
R e c a ll T im e r e xp ire s
C ancel R e c a ll
R e d ire c t c a ll to u s e r A S to p R e c a ll tim e r NO
s u c c e s s fu l?
YE S
ID L E
further action is beyond the scope of this Standard
R e c a ll N o tif ic a t io n to u s e r A
C a n c e l tra n s f e r, re le a s e u s e r C
th is a c tio n m a y b e d e fe rre d u n til u s e r A is a le rte d
R e c a ll D e liv e re d
N o a nswe r fro m u s e r A
further action is beyond the scope of this Standard
U se r A a n s w e rs re c a ll
R e c a ll N o tify B , A a n s w e re d
ID L E
Figure 1 - SS-RE, Overall SDL
User A Alerting
R e c a ll N o tify B , A A le rtin g
Recall Delivered
- 8 -
7
SS-RE stage 2 specification
7.1
Functional model
7.1.1
Functional model description The functional model shall comprise the following functional entities (FEs): FE1 FE2 FE3 FE4
Served user's service agent Recall Execute entity Recall Status Receive entity Transferred user's service agent
The following functional relationships shall exist between these FEs: rw rx
between FE1 and FE2 between FE2 and FE3 and between FE3 and FE4
Figure 2 shows these FEs and relationships.
USER A
FE1
rw
FE2
rx
rx
FE3
FE4
USER B
F ig u r e 2 - F u n c t io n a l m o d e l f o r S S - R E 7.1.2 D e s c r ip t io n o f f u n c t io n a l e n t it ie s 7.1.2.1 S e r v e d u s e r 's s e r v ic e a g e n t f u n c t io n a l e n t it y F E1 This functional entity receives on behalf of the served user the indication that an incoming call has been re-directed as a result of recall timer expiry. 7.1.2.2
R e c a ll Ex e c u t e f u n c t io n a l e n t it y F E2 This functional entity is responsible for the recall timing function and for redirection of the transferred call to the served user when the recall timer expires. FE2 informs FE3 that the served user is being alerted and/or has answered after recall has occurred.
7.1.2.3
Recall Status Receive functional entity FE3 This functional entity receives the information flow indicating the alerting/answered state of the served user after recall has occurred and passes this information on to FE4.
7.1.2.4
Transferred user's service agent functional entity FE4 This functional entity informs the transferred user that recall has occurred.
7.1.3
R e la t io n s h ip o f f u n c t io n a l m o d e l t o b a s ic c a ll f u n c t io n a l m o d e l An example of a relationship between the FEs for SS-RE and FEs for the basic call is shown in figure 3.
FE1
CCA
rw r1
FE2
CC
Transferring USER A
rx r2
FE3
CC
rx r3
FE4 CCA
Transferred USER B
Figure 3 - Example relationship between the model for SS-RE and the Basic Call Model
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7.2
Information flows
7.2.1
7.2.1.1
D e f in it io n o f in f o r m a t io n f lo ws In the tables listing the elements in information flows, the column headed "Request" indicates which of these elements are mandatory (M) and which are optional (O) in a request/indication information flow. r w_ I n f o r m rw_Inform is an unconfirmed information flow across rw from FE2 to FE1 which informs the served user that the incoming call is recalling. Table 2 lists the elements within the rw_Inform information flow. Table 2 - Content of rw_Inform Element
Request
Unanswered Number (Note 1)
M
Recall Reason (Note 2)
M
Note 1 This element contains user C's number if known and not restricted, or the called number otherwise. Note 2 Allowed values are 'busy' and 'no answer'.
7.2.1.2
rx_Inform1 rx_Inform1 is an unconfirmed information flow from FE2 to FE3 and from FE3 to FE4 which is used to indicate that Recall has occurred and that user A is alerting. Table 3 lists the elements within the rx_Inform1 information flow. Ta b le 3 - C o n t e n t o f r x _ I n f o r m 1 Element
7.2.1.3
Request
Alerted Number
O
Alerted Name
O
rx_Inform2 rx_Inform2 is an unconfirmed information flow from FE2 to FE3 and from FE3 to FE4 which is used to indicate that user A has answered. Table 4 lists the elements within the rx_Inform2 information flow. Ta b le 4 - C o n t e n t o f r x _ I n f o r m 2 Element
7.2.2
Request
Connected Number (CN)
M
Connected Subaddress (CS)
O
Connected Name
O
R e la t io n s h ip o f in f o r m a t io n f lo ws t o Ba s ic C a ll in f o r m a t io n f lo ws rw_Inform request/indication shall be sent with r1_SETUP request/indication. All other information flows shall be sent independently of basic call information flows.
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7.2.3
Ex a m p le o f in f o r m a t io n f lo w s e q u e n c e s A stage 3 standard for SS-RE shall provide signalling procedures in support of the information flow sequence specified below. In addition, signalling procedures should be provided to cover other sequences arising from error situations, interactions with basic call, interactions with other supplementary services and ANFs, different topologies, etc.. In the figure, SS-RE information flows are represented by solid arrows and basic call information flows are represented by broken arrows. An ellipse embracing two information flows indicates that the two information flows occur simultaneously. Within a column representing an SS-RE functional entity, the numbers refer to functional entity actions listed in 7.3.
7.2.3.1
N o r m a l o p e r a t io n o f S S - R E Figure 4 shows the information flow sequence for normal operation of SS-RE following a transfer initiated by user A.
FE1
rw
CCA
r1
CC
rw_Inform req.ind.
201
101
FE2
rx
FE3
rx
r2
CC
r3
301
rx_Inform1
FE4 CCA
r1_SETUP req/ind r1_ REPORT req/ind r1_SETUP res/con
202
rx_Inform1 req/ind
203
req/ind
401
rx_Inform2 req/ind
302
rx_Inform2 req/ind
402
94-0152-A
F i g u r e 4 - I n f o r m a t i o n f l o w s e q u en c e - N o r m a l o p e r a t i o n o f S S - R E
7.3
Functional entity actions The following FE actions shall occur at the points indicated in figure 4.
7.3.1
F u n c t io n a l e n t it y a c t io n s o f F E1 101 Deliver SS-RE notifications to the user as received from FE2 in rw_Inform.
7.3.2
F u n c t io n a l e n t it y a c t io n s o f F E2 201 On receipt of an indication that the transferred call is alerting or waiting at busy user C, start the appropriate SS-RE timer. As soon as the alerting or wait-on-busy condition ceases for any reason, stop the SS-RE timer and terminate SS-RE. Following expiry of the recall timer, send the rw_Inform request/indication information flow to FE1 with basic call flow r1_SETUP request/indication, and optionally cancel the transfer process and disconnect the call to user C. 202
On receipt of r1_REPORT request/indication send rx_Inform1 request/indication to FE3 and disconnect the call to user C, if not already done.
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203 7.3.3
F u n c t io n a l e n t it y a c t io n s o f F E3 301 Receive rx_Inform1 request/indication from FE2, and send rx_Inform1 request/indication to FE4. 302
7.3.4
Receive rx_Inform2 request/indication from FE2, and send rx_Inform2 request/indication to FE4.
F u n c t io n a l e n t it y a c t io n s o f F E4 401 Deliver SS-RE notification and alerted party information to user B as received from FE3 in rx_Inform1. 402
7.4
On receipt of r1_SETUP response/confirmation send rx_Inform2 request/indication to FE3.
Deliver SS-RE notification and connected party information to user B as received from FE3 in rx_Inform2.
Functional entity behaviour The FE behaviours shown below are intended to illustrate typical FE behaviour in terms of information flows sent and received. The behaviour of each FE is shown using the Specification and Description Language (SDL) defined in ITU-T Rec. Z.100.
7.4.1
Be h a v io u r o f F E1 Figure 5 shows the normal behaviour of FE1. Output signals to the left represent primitives to user A. Input signals from the right represent information flows from FE2.
FE1 Idle
rw_Inform req/ind
Recall_Notify
FE1 Idle
Figure 5 - SS-RE SDL for functional entity FE1 7.4.2
Be h a v io u r o f F E2 Figure 6 shows the behaviour of FE2. Output symbols to the left represent information flows to FE1. Input symbols from the right represent internal stimuli or stimuli from basic call. Output signals to the right represent information flows to FE3.
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F E 2 Idle
Tra n s fe r occ urre d or u se r C is a le rte d a fte r h av ing b ee n bu sy start appropriate recall timer
F E 2 re ca ll tim ing
C a nce l R e ca ll
R eca ll Time r e x pire s
Stop Recall timer
rw_Inform re q/ind
F E 2 Idle
cancel transfer and release user C
with b a s ic c a ll s e tup r e qu e s t
this a ction occurs only once , a t e ithe r of the se point s in th e c ontrol flow
FE2 W a it for se rve d u se r a ns w e r
e .g. ca ll re le a se d, no answer from served use r, etc.
F a ilure indica tion
cancel transfer and release user C
B C -S e tup confirmation re ce ive d
B C -R e port indica tion re ce ive d
cancel transfer and release user C
cancel transfer and release user C
rx_Inform 2 re q/ind
rx_Inform 1 re q/ind
F E 2 Idle
FE2 W a it for se rve d u se r a ns we r
Figure 6 - SS-RE SDL for functional entity FE2
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7.4.3
Be h a v io u r o f F E3 Figure 7 shows the behaviour of FE3. Input symbols from the left represent information flows from FE2. Output symbols to the right represent information flows to FE4.
FE3 Idle
rx_Inform2 req/ind (answered)
rx_Inform1 req/ind (alerting)
rx_Inform2 req/ind
rx_Inform1 req/ind
FE3 Idle
Figure 7 - SS-RE SDL for functional entity FE3 7.4.4
Be h a v io u r o f F E4 Figure 8 shows the behaviour of FE4. Input symbols from the left represent information flows from FE3. Output symbols to the right represent primitives to user B.
FE4 Idle
rx_Inform2 req/ind (answered)
rx_Inform1 req/ind (alerting)
Recalled user answered
Recalled user alerting
FE4 Idle
Figure 8 - SS-RE SDL for functional entity FE4
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7.5
Allocation of functional entities to physical equipment The allocations of FEs to physical equipment shown in table 5 shall apply. In the table, "TE" represents a TE attached to a PISN. Where a terminal is stimulus with respect to SS-RE, any FE shown as residing in the TE shall reside instead in that TE's local PINX. T a b l e 5 - S c e n a r i o s f o r t h e a l l o c a t io n o f F E s t o p h y s i c a l e q u i p m e n t Functional entities Scenarios
User A
User B
FE1
FE2
FE3
FE4
1
TE
PINX
PINX
TE
2
TE
PINX
Gateway PINX
other network
3
other network
other network
PINX
TE
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