One document matched: draft-elwell-sipping-qsig2sip-diversion-00.txt
Internet Engineering Task Force J. Elwell
Internet Draft Siemens
J. McMillen
Avaya Inc.
JF. Rey/O. Rousseau
draft-elwell-sipping-qsig2sip-diversion-00.txt Alcatel
Expires: December 2003 June 2003
Interworking between SIP and QSIG for call diversion
Status of this Memo
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of Section 10 of RFC 2026 except that the right to produce derivative
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Abstract
This document specifies call diversion interworking between the
Session Initiation Protocol (SIP) and QSIG within corporate
telecommunication networks (also known as enterprise networks). SIP
is an Internet application-layer control (signalling) protocol for
creating, modifying, and terminating sessions with one or more
participants. These sessions include, in particular, telephone calls.
QSIG is a signalling protocol for creating, modifying and terminating
circuit-switched calls, in particular telephone calls, within Private
Integrated Services Networks (PISNs). QSIG is specified in a number
of ECMA Standards and published also as ISO/IEC standards.
As the support of telephony within corporate networks evolves from
circuit-switched technology to Internet technology, the two
technologies will co-exist in many networks for a period, perhaps
several years. Therefore there is a need to be able to establish,
modify and terminate sessions involving a participant in the SIP
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network and a participant in the QSIG network, taking into account
the impact of diversion during call establishment. Such calls are
supported by gateways that perform interworking between SIP and QSIG.
This document is a product of the authors' activities in ECMA
(www.ecma.ch) on interoperability of QSIG with IP networks.
1 Introduction....................................................3
2 Terminology.....................................................4
3 Definitions.....................................................4
3.1 External definitions..........................................4
3.2 Other definitions.............................................4
3.2.1 Call diversion..............................................4
3.2.2 Call forwarding busy (CFB)..................................5
3.2.3 Call forwarding no reply (CFNR).............................5
3.2.4 Call forwarding unconditional (CFU).........................5
3.2.5 Corporate telecommunication Network (CN)....................5
3.2.6 Entity A....................................................5
3.2.7 Entity B....................................................5
3.2.8 Entity C....................................................5
3.2.9 Gateway.....................................................5
3.2.10 IP network.................................................5
3.2.11 Leg A......................................................6
3.2.12 Leg B......................................................6
3.2.13 Leg C......................................................6
3.2.14 Private Integrated Services Network (PISN).................6
3.2.15 Private Integrated services Network eXchange (PINX)........6
3.2.16 Rerouting entity...........................................6
3.2.17 User A.....................................................6
3.2.18 User B.....................................................6
3.2.19 User C.....................................................6
4 Acronyms........................................................6
5 Background and architecture for SIP-QSIG interworking...........7
6 Call diversion..................................................7
7 Call diversion in QSIG..........................................9
8 Call diversion in SIP..........................................10
9 Diversion interworking.........................................11
9.1 Scenarios for diversion interworking.........................11
9.2 Mapping of numbers and URIs..................................12
9.3 Derivation of QSIG diversion reasons.........................12
9.3.1 Scenario A1................................................13
9.3.2 Scenario B1................................................13
9.3.3 Scenario C2................................................13
9.4 Derivation of SIP response codes (scenarios A2 and C1).......14
9.5 Mapping the QSIG diversion counter...........................14
9.6 Interworking for scenario A1.................................14
9.7 Interworking for scenario A2.................................14
9.8 Interworking for scenario B1.................................14
9.9 Interworking for scenario B2.................................14
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9.10 Interworking for scenario C1................................14
9.11 Interworking for scenario C2................................15
10 Example message sequences.....................................15
10.1 Scenario A1.................................................15
10.1.1 Successful call û history information in 200 response.....15
10.1.2 Successful call û history information in provisional response
.................................................................16
10.1.3 Failed call...............................................17
10.2 Scenario A2.................................................18
10.2.1 Successful call û CFU or CFB..............................18
10.2.2 Successful call û CFNR....................................20
10.3 Scenario B1.................................................20
10.3.1 Successful diversion û CFU or CFB.........................20
10.3.2 Successful diversion û CFNR...............................22
10.3.3 Failure û callRerouting.err received......................23
10.3.4 Failure û No answer following CFNR........................24
10.4 Scenario B2.................................................25
10.4.1 Successful diversion......................................25
10.5 Scenario C1.................................................26
10.6 Scenario C2.................................................27
10.7 Scenario A1 followed by B1..................................28
10.8 Scenario A2 followed by scenario B2.........................29
10.9 Scenario C1 followed by scenario A1.........................30
10.10 Scenario C2 followed by scenario A2........................31
10.11 Scenario C1 followed by scenario B1........................32
10.12 Scenario C2 followed by scenario B2........................33
11 Security considerations.......................................34
12 Author's Addresses............................................34
13 Normative References..........................................34
Annex A - Change log.............................................35
1 Introduction
This document specifies signalling interworking between "QSIG" and
the Session Initiation Protocol (SIP) in support of call diversion
within a corporate telecommunication network (CN).
"QSIG" is a signalling protocol that operates between Private
Integrated Services eXchanges (PINX) within a Private Integrated
Services Network (PISN). A PISN provides circuit-switched basic
services and supplementary services to its users. QSIG is specified
in ECMA Standards, in particular [2] (call control in support of
basic services), [3] (generic functional protocol for the support of
supplementary services) and a number of Standards specifying
individual supplementary services. Diversion services are specified
in [5] and the QSIG signalling protocol in support of these services
is specified in [6]. In particular, this signalling protocol signals
information about call diversion to the users involved.
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SIP is an application layer protocol for establishing, terminating
and modifying multimedia sessions. It is typically carried over IP
[10], [11]. Telephone calls are considered as a type of multimedia
session where just audio is exchanged. SIP is defined in [1]. An
extension to SIP provides history information [8] that can be used to
signal information about the retargeting of a request, in particular
a call establishment request, as it is routed through a network.
This document specifies signalling interworking for call diversion
during the establishment of calls between a PISN employing QSIG and a
corporate IP network employing SIP. It covers both the impact on SIP
of call diversion in the QSIG network and the impact on QSIG of
request retargeting in the SIP network. Signalling interworking for
call diversion operates on top of signalling interworking for basic
calls, which is specified in [9]
Call diversion interworking between a PISN employing QSIG and a
public IP network employing SIP is outside the scope of this
specification. However, the functionality specified in this
specification is in principle applicable to such a scenario when
deployed in conjunction with other relevant functionality (e.g.,
number translation, security functions, etc.).
This specification is applicable to any interworking unit that can
act as a gateway between a PISN employing QSIG and a corporate IP
network employing SIP.
2 Terminology
In this document, the key words "MUST", "MUST NOT", "REQUIRED",
"SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",
and "OPTIONAL" are to be interpreted as described in RFC 2119 [4] and
indicate requirement levels for compliant SIP implementations.
3 Definitions
For the purposes of this specification, the following definitions
apply.
3.1 External definitions
The definitions in [2] and [1] apply as appropriate.
3.2 Other definitions
3.2.1 Call diversion
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The act of retargeting a call during call establishment by changing
the user identity that is used as the basis for routing to the
destination.
3.2.2 Call forwarding busy (CFB)
Call diversion invoked because the targeted user is busy.
3.2.3 Call forwarding no reply (CFNR)
Call diversion invoked because the targeted user fails to reply
within a certain time.
3.2.4 Call forwarding unconditional (CFU)
Call diversion invoked for reasons other than those leading to CFB or
CFNR.
3.2.5 Corporate telecommunication Network (CN)
Sets of privately-owned or carrier-provided equipment that are
located at geographically dispersed locations and are interconnected
to provide telecommunication services to a defined group of users.
NOTE. A CN can comprise a PISN, a private IP network (intranet) or a
combination of the two.
NOTE. Also known as enterprise network.
3.2.6 Entity A
The entity that provides information about diversion to user A.
3.2.7 Entity B
The entity that invokes diversion for a call targeted at user B.
3.2.8 Entity C
The entity that provides information about diversion to user C.
3.2.9 Gateway
An entity that performs interworking between a PISN using QSIG and an
IP network using SIP.
3.2.10 IP network
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A network, unless otherwise stated a corporate network, offering
connectionless packet-mode services based on the Internet Protocol
(IP) as the network layer protocol.
3.2.11 Leg A
The call segment between entity A and the rerouting entity for a call
that undergoes diversion.
3.2.12 Leg B
The call segment between the rerouting entity and entity B for a call
that undergoes diversion.
3.2.13 Leg C
The call segment between the rerouting entity and entity C for a call
that undergoes diversion.
3.2.14 Private Integrated Services Network (PISN)
A CN or part of a CN that employs circuit-switched technology.
3.2.15 Private Integrated services Network eXchange (PINX)
A PISN nodal entity comprising switching and call handling functions
and supporting QSIG signalling in accordance with [2].
3.2.16 Rerouting entity
The entity that performs call rerouting on request from entity B and
that provides information about diversion to entity A and entity C.
3.2.17 User A
The calling user of a call that undergoes diversion.
3.2.18 User B
The user on behalf of which call diversion is invoked for an incoming
call to that user.
3.2.19 User C
The user to which a call is diverted.
4 Acronyms
APDU Application Protocol Data Unit
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CFB Call forwarding busy
CFNR Call forwarding no reply
CFU Call forwarding unconditional
IP Internet Protocol
PINX Private Integrated services Network eXchange
PISN Private Integrated Services Network
SIP Session Initiation Protocol
UA User Agent
UAC User Agent Client
UAS User Agent Server
5 Background and architecture for SIP-QSIG interworking
The background and architecture of [9] applies. In addition, the
interworking function in the protocol model handles interworking for
call diversion services. This involves interworking between the QSIG
call diversion protocol specified in [6] and SIP, including the use
of SIP request history information as specified in [8].
6 Call diversion
Call diversion, as specified in QSIG and for the purposes of this
document, is the act of retargeting a call during call establishment
by changing the user identity that is used as the basis for routing
to the destination. This can be viewed as being a change of
destination user, although in some cases two identities can belong to
the same user, e.g., a home number and office number. The three users
involved are known as user A (the calling user A), user B (the called
user or diverting user) and user C (the diverted-to user).
Reasons for invoking diversion are various and can depend on factors
such as the state of the line serving user B, the time of day and the
type or identity of user A. It could also be as a result of action by
user B(sometimes known as call deflection). A diversion can occur
immediately. i.e., without alerting user B, or after a period of
alerting without reply. With the exception of call deflection,
diversion requirements must be pre-configured into some equipment
acting on behalf of user B, e.g, a telephone, a PINX or a SIP proxy.
This could be achieved, for example, by rules-based scripting.
It is often useful or even important that the users involved in a
diverted call (user A and user C) are informed of the diversion. This
can be particularly important for automata, e.g., for a call diverted
to a voice mail system it might be important to indicate to the
system that the call has been diverted from user B. However, privacy
considerations can sometimes lead to the suppression of this
information.
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The general model for a call that undergoes diversion is shown in
Figure 1. Entity B is the entity that invokes diversion, based on
configuration or, in the case of call deflection, on request from
user B. The Rerouting entity performs call rerouting on instruction
from Entity B and provides information about the diversion to Entity
A and Entity C. Entity A and Entity C handle diversion on behalf of
users A and C respectively by providing information about diversion.
(1)
-------------------------------------->
(2)
<--------------
+--------+
Leg B | |
+-----------|Entity B|
| | |
+--------+ +---------+ | +--------+
| | Leg A | |--+
|Entity A|-------------|Rerouting|
| | | entity |--+
+--------+ +---------+ | +--------+
(4) | Leg C | |
<-------------- +-----------|Entity C|
| |
(3) +--------+
-------------->
Figure 1 û Logical model for diversion in a QSIG network
From this model it can be seen that there are three call legs:
- leg A between Entity A and the Rerouting entity (null if these two
entities are collocated);
- leg B between Entity B and the Rerouting entity (null if these two
entities are collocated);
- leg C between Entity C and the Rerouting PINX (null if PINX C and
the rerouting PINX are the same).
Diversion signalling on leg A provides information about diversion to
Entity A, which can use it to provide information to user A.
Diversion signalling on leg B instructs the Rerouting entity to carry
out rerouting. Diversion signalling on leg C provides information
about diversion to Entity C, which can use it to provide information
to user C.
Figure 1 also illustrates the basic dynamic behaviour:
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(1) Call establishment from user A as far as Entity B.
(2) Rerouting request from Entity B to Rerouting Entity.
(3) Rerouted call establishment from Rerouting Entity to Entity C
accompanied by information about the diversion.
(4) Information about the diversion from the Rerouting entity to
Entity A.
Diversions can be chained. In this case the rerouted call from the
Rerouting entity reaches another Entity B. The same or a different
Rerouting entity then reroutes the call towards the new user C.
7 Call diversion in QSIG
Call diversion in QSIG is the act of retargeting a call during call
establishment by changing the called party number, which is the user
identity used as the basis for routing to the destination. Call
diversion in QSIG follows the model described above. Entity A is
located in user AÆs PINX (PINX A), Entity B is located in user BÆs
PINX (PINX B) and Entity C is located in user CÆs PINX (PINX C). The
Rerouting entity is located either at user BÆs PINX (diversion by
forward switching) or at user AÆs PINX (diversion by rerouting).
Because of potential interactions with other supplementary services,
the signalling for which passes transparently through intermediate
(Transit) PINXs, the rerouting PINX is constrained to be either PINX
B or PINX A. The former case is known as diversion by forward
switching, and is analogous to SIP retargeting by a proxy. The latter
case is known as diversion by rerouting and is analogous to SIP
retargeting by redirection.
For the purposes of QSIG, diversions are classified into one of the
following types:
- call forwarding no reply (CFU)(forwarding as a result of no user
reply after alerting user B for a certain time);
- call forwarding busy (CFB)(forwarding as a result of user BÆs
device being busy); and
- call forwarding unconditional (CFU)(forwarding for reasons other
than no reply or busy).
NOTE. CFU is not necessarily entirely unconditional, since it can
depend on other factors, e.g., time of day.
In common with other supplementary services, QSIG signalling for
diversion is based on [3] and comprises the following remote
operations:
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- callRerouting - this confirmed operation is applicable to leg B and
provides a means for PINX B to request the Rerouting PINX to reroute
a call to user C.
- cfnrDivertedLegFailed û this unconfirmed operation is applicable to
leg B and indicates failure to establish call leg C subsequent to
accepting a callRerouting operation. cfnrDivertedLegFailed applies
only to CFNR (i.e. to diversions after user B has been alerted) and
indicates to PINX B that user B should continue to be alerted. For
other types of diversion leg B is cleared down as soon as the
callRerouting operation is accepted, without waiting to see if the
call towards user C can be established.
- divertingLegInformation1 - this unconfirmed operation is applicable
to leg A and signals information about the diversion to PINX A,
including any privacy requirement of user B to prevent disclosure of
diversion information to user A. Note that PINX A can use the
information for internal purposes (e.g., call logging) but is trusted
not to disclose private information to user A.
- divertingLegInformation2 û this unconfirmed operation is applicable
to leg C and signals information about the diversion to PINX C.
- divertingLegInformation3 û this unconfirmed operation is applicable
to legs A and C and signals privacy information from PINX C to PINX
A. This privacy information provides the possibility for user C to
suppress the disclosure of its identity to user A. PINX A must take
into account both the privacy information in divertingLegInformation1
and the privacy information in divertingLegInformation3 before
disclosing information to user A.
Chained diversions are supported. PINX A receives a
divertingLegInformation1 operation for each diversion, but often a
divertingLegInformation3 operation only for the final diversion
(since this information is not necessarily available until answer).
The final PINX C receives a single divertingLegInformation2 operation
containing information about the first and last diversions but not
intermediate diversions.
8 Call diversion in SIP
Call diversion is not specified for SIP. However, SIP does have the
concept of retargeting an INVITE request. This occurs at a proxy,
instigated either by the proxy itself or on request from a redirect
using a 3xx response. Relating this to the model, the Rerouting
entity for a SIP diversion is the proxy that retargets the INVITE
request. Entity B is either that same proxy or a redirect that issues
a 3xx response. A 3xx response therefore has some synergy with a QSIG
callRerouting operation. Entity A is the UAC for the INVITE request
and Entity C is the UAS of the retargeted-to user.
Retargeting involves changing the Request-URI within the INVITE
request, this field being the basis for routing the request.
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[1] does not provide signalling support for notifying user AÆs UA or
user CÆs UA that retargeting has occurred. Additional signalling for
this purpose is specified in [8], in accordance with requirements
specified in [7]. This allows a retargeting proxy to insert a
History-Info header into a request when it is forwarded downstream,
i.e. on leg C towards Entity C. Moreover Entity C reflects the
received History-Info header back over leg C and leg A towards Entity
A. In this way, both Entity A and Entity C receive information about
the retarget and can provide this information to their respective
users.
Chained retargets are supported. Entity A and Entity C receive
information about multiple retargets carried out by various proxies
along the path taken by the INVITE request.
9 Diversion interworking
9.1 Scenarios for diversion interworking
From the descriptions in sections 7 and 8 it can be seen that both
diversion in QSIG and retargeting, along with the History-Info
header, in SIP can be mapped to the call diversion model described in
section 6. Therefore interworking can be described in terms of this
model.
Interworking can occur on leg A, on leg B or on leg C. In either
case, the Rerouting entity can be in either the SIP network or the
QSIG network. This leads to 6 interworking scenarios.
- Scenario A1: interworking on leg A, call from QSIG to SIP
undergoing retargeting in the SIP network. Entity A in QSIG network,
Rerouting entity, Entity B and Entity C in SIP network.
- Scenario A2: interworking on leg A, call from SIP to QSIG
undergoing diversion in the QSIG network. Entity A in SIP network,
Rerouting entity, Entity B and Entity C in QSIG network.
- Scenario B1: interworking on leg B, call from QSIG to SIP where
QSIG network performs rerouting in response to a redirection request
from the SIP network. Entity A, Entity C and Rerouting entity in QSIG
network, Entity B in SIP network.
- Scenario B2: interworking on leg B, call from SIP to QSIG where SIP
network performs retargeting in response to a rerouting request from
the QSIG network. Entity A, Entity C and Rerouting entity in SIP
network, Entity B in QSIG network.
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- Scenario C1: interworking on leg C, call diverted by QSIG network
to destination in SIP network. Entity A, Entity B and Rerouting
entity in QSIG network, Entity C in SIP network.
- Scenario C2: interworking on leg C, call retargeted by SIP network
to destination in QSIG network. Entity A, Entity B and Rerouting
entity in SIP network, Entity C in QSIG network.
Call diversion interworking can occur more than once for a given call
(chained diversions). The different instances of interworking can be
on the same leg (where a leg passes through two or more gateways) or
on different legs. For example, Entity A could be in a QSIG network,
Rerouting Entity and Entity B could be in a SIP network, and Entity C
could be in a QSIG network. In this case interworking occurs on leg A
(scenario A1) and on leg C (scenario C2). Each instance of
interworking conforms to one of the 6 scenarios listed above. No new
interworking scenario is introduced as a result.
Chained diversions can introduce mixed scenarios whereby a particular
gateway plays the role of one scenario for the one diversion and
either the same scenario or a different scenario for the next
diversion. For example, consider a gateway performing a scenario C1
role as the result of diversion in the QSIG network (Rerouting entity
in the QSIG network) to a diverted-to user in the SIP network. The
gateway can also perform the role of scenario A1 if a further
diversion occurs in the SIP network (Rerouting Entity in the SIP
network).
9.2 Mapping of numbers and URIs
Most of the examples shown in section 10 involve mapping of
identifiers, e.g., the identifier representing the diverted to user
or the identifier representing the diverting user. In QSIG users are
identified by numbers. In SIP users are identified by URIs. Mapping
of identifiers is described in detail in [12].
In some cases it may not be possible for a gateway to map a SIP URI
to a QSIG number or vice versa. If it is not possible to derive an
identifier that is essential for generating a signalling element
relating to diversion, unless otherwise stated the call should be
allowed to continue without that signalling element.
9.3 Derivation of QSIG diversion reasons
The History-Info header contains one or more retargeted-to-URIs, each
containing a Reason header as an optional parameter. The Reason
header contains the reason for retargeting. Some of the scenarios
require the derivation of a QSIG diversionReason element (indicating
CFU, CFB or CFNR), and the Reason header, where available, is the
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most suitable source of information for this. Although the Reason
header contains provision for reason codes other than SIP response
codes, normally it will contain a SIP response code, particularly if
it has originated at a native SIP entity as opposed to a gateway.
There needs to be a default diversionReason to cater for cases where
the Reason header is omitted or where it contains a reason that does
not readily suggest a particular diversionReason.
The particular mapping will depend on the scenario concerned.
9.3.1 Scenario A1
In QSIG, diversionReason CFNR is theoretically meaningful only after
ALERTING. Also for the first diversion after ALERTING theoretically
the only meaningful diversionReason is CFNR. However, in practice
violating these rules will probably not cause problems at downstream
PINXs.
SIP response codes do not readily distinguish between the three
diversionReason values, and therefore taking account of whether
ALERTING has been sent is perhaps beneficial in selecting a more
meaningful diversionReason value.
The following rules are proposed:
1. If the reason code in the Reason header is 486 (Busy Here) or 600
(Busy Everywhere), map to CFB.
2. Otherwise if ALERTING has previously been sent, map to CFNR.
3. Otherwise map to CFU.
9.3.2 Scenario B1
History-Info is not normally contained in the 3xx response (except to
denote previous retargets), and therefore there is no Reason header
and the only source of information is the 3xx response code. The
various 3xx response codes do not readily map to diversion reasons.
The following rules are proposed:
1. If ALERTING has previously been sent, map to CFNR.
2. Otherwise map to CFU.
9.3.3 Scenario C2
In this scenario it is not possible to determine whether alerting was
achieved prior to diversion. The following rules are proposed:
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1. If the reason code in the Reason header is 486 (Busy Here) or 600
(Busy Everywhere), map to CFB.
2. If the reason code in the Reason header is 480 (Temporarily
Unavailable), map to CFNR.
3. Otherwise map to CFU.
9.4 Derivation of SIP response codes (scenarios A2 and C1)
The diversionReason in divertingLegInformation1 and
divertingLegInformation2 should ideally be mapped to a corresponding
reason in the History-Info header, i.e., to the Reason header
parameter of the retargeted-to-URI. Although there is provision for
the Reason header to contain reasons other than SIP response codes,
other reasons are less likely to be meaningful to the majority of
implementations. Therefore it would be better to map diversionReason
to appropriate SIP response codes. The following is proposed.
1. Map CFU to 302 (Moved Temporarily).
2. Map CFB to 486 (Busy Here).
3. Map CFNR to 480 (Temporarily Unavailable).
9.5 Mapping the QSIG diversion counter
EDITOR'S NOTE. To be added.
9.6 Interworking for scenario A1
EDITOR'S NOTE. To be added.
9.7 Interworking for scenario A2
EDITOR'S NOTE. To be added.
9.8 Interworking for scenario B1
EDITOR'S NOTE. To be added.
9.9 Interworking for scenario B2
EDITOR'S NOTE. To be added.
9.10 Interworking for scenario C1
EDITOR'S NOTE. To be added.
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9.11 Interworking for scenario C2
EDITOR'S NOTE. To be added.
10 Example message sequences
In the interests of keeping the diagrams simple, ACK and PRACK are
not shown.
The following notation is used for diversion information within QSIG
messages:
- xxx.inv û invoke application protocol data unit (APDU) of operation
xxx.
- xxx.res û return result APDU of operation xxx.
- xxx.err û return error APDU of operation xxx.
10.1 Scenario A1
Call from QSIG to SIP undergoes diversion in SIP network.
10.1.1 Successful call û history information in 200 response
+--------------+
PISN | Interworking | IP network
| unit |
+--------------+
||
QSIG SETUP ||
--------------------------->||
||
QSIG CALL PROCEEDING || INVITE req
<---------------------------|| Supported: HistInfo
||--------------------------->
||
|| 100
||<---------------------------
||
|| 180
QSIG ALERTING ||<---------------------------
<---------------------------||
|| 200
|| History-Info
QSIG CONNECT ||<---------------------------
divertingLegInformation1.inv||
divertingLegInformation3.inv||
<---------------------------||
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Interworking between SIP and QSIG June 2003
||
Figure 2 û Example of scenario A1 û successful call û history
information in 200 response
NOTE 1. Normally the first targeted-to URI in the History-Info header
will be the original targeted-to URI (the Request-URI in the INVITE
request sent by the gateway), and therefore this URI can be
discarded. The second targeted-to URI should be used to derive the
number in divertingLegInformation1.inv.
NOTE 2. If there is more than one targeted-to URI (in addition to the
original targeted-to URI) it would be possible to include more than
one divertingLegInformation1 invoke in the CONNECT message.
NOTE 3. The diversionReason in divertingLegInformation1 needs to be
derived from the History-Info header. See section 9.3.
10.1.2 Successful call û history information in provisional response
+--------------+
PISN | Interworking | IP network
| unit |
+--------------+
||
QSIG SETUP ||
--------------------------->||
||
QSIG CALL PROCEEDING || INVITE req
<---------------------------|| Supported: HistInfo
||--------------------------->
||
|| 100
||<---------------------------
||
|| 180
|| History-Info
QSIG ALERTING ||<---------------------------
divertingLegInformation1.inv||
divertingLegInformation3.inv||
<---------------------------||
|| 200
|| History-Info
QSIG CONNECT ||<---------------------------
<---------------------------||
||
Figure 3 û Example of scenario A1 û successful call û history
information in provisional response
Elwell et alia Expires - December 2003 [Page 16]
Interworking between SIP and QSIG June 2003
NOTE 1. This shows History-Info arriving in a 180 response. An
alternative would be receipt of History-Info in a 183 response, in
which case the divertingLegInformation1.inv would be sent in the
PROGRESS message (if a PROGRESS message is to be sent) or in a
FACILITY message.
NOTE 2. Normally the first targeted-to URI in the History-Info header
will be the original targeted-to URI (the Request-URI in the INVITE
request sent by the gateway), and therefore this URI can be
discarded. The second targeted-to URI should be used to derive the
number in divertingLegInformation1.inv.
NOTE 3. If there is more than one targeted-to URI (in addition to the
original targeted-to URI) it would be possible to include more than
one divertingLegInformation1 invoke in the ALERTING (or PROGRESS or
FACILITY) message.
NOTE 4. The diversionReason in divertingLegInformation1 needs to be
derived from the History-Info header. See section 9.3.
NOTE 5. The divertingLegInformation3.inv is shown as being sent in
the same message as the divertingLegInfo1.inv. This is because SIP
has no means of indicating later that the retargeted-to URI in the
History-Info header is not to be disclosed to the calling user. In a
QSIG environment the divertingLegInformation3.inv cannot be sent
until it is clear that the diverted-to user does not require privacy,
and therefore it is often deferred until the CONNECT message. A
gateway could choose to defer until the CONNECT message, but there is
no need.
NOTE 6. If further provisional responses are received with extended
information in the History-Info header, the additional targeted-to
URIs can be used to generate further divertingLegInformation1 and
divertingLegInformation3 invokes.
NOTE 7. Another History-Info header will be present in the 200 OK
response. Unless this contains additional targeted-to URIs, no
divertingLegInformation1.inv should be included in the CONNECT
message.
10.1.3 Failed call
+--------------+
PISN | Interworking | IP network
| unit |
+--------------+
||
QSIG SETUP ||
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Interworking between SIP and QSIG June 2003
--------------------------->||
||
QSIG CALL PROCEEDING || INVITE req
<---------------------------|| Supported: HistInfo
||--------------------------->
||
|| 100
||<---------------------------
||
|| 4xx/5xx/6xx
|| History-Info
QSIG FACILITY ||<---------------------------
divertingLegInformation1.inv||
divertingLegInformation3.inv||
<---------------------------||
||
QSIG DISCONNECT ||
<---------------------------||
||
QSIG RELEASE ||
--------------------------->||
||
QSIG RELEASE COMPLETE ||
<---------------------------||
||
Figure 4 û Example of scenario A1 û failed call
10.2 Scenario A2
Call from SIP to QSIG undergoes diversion in QSIG network.
10.2.1 Successful call û CFU or CFB
+--------------+
IP network | Interworking | PISN
| unit |
+--------------+
||
INVITE req ||
Supported: HistInfo ||
--------------------------->||
|| QSIG SETUP
100 ||--------------------------->
<---------------------------||
|| QSIG CALL PROCEEDING
||<---------------------------
||
|| QSIG FACILITY
Elwell et alia Expires - December 2003 [Page 18]
Interworking between SIP and QSIG June 2003
||divertingLegInformation1.inv
||<---------------------------
||
|| QSIG ALERTING
180 ||<---------------------------
<---------------------------||
|| QSIG CONNECT
200 ||divertingLegInformation3.inv
History-Info ||<---------------------------
<---------------------------||
||
Figure 5 û Example of scenario A2 (CFU or CFB)
NOTE 1. In the History-Info header, the first targeted-to URI should
be the Request-URI in the received INVITE request and the second
targeted-to URI should be derived from the number in the
divertingLegInformation1.inv. If more than one
divertingLegInformation1.inv have been received in the same QSIG
message or previous QSIG messages, additional targeted-to URIs can be
derived.
NOTE 2. History-Info should be omitted if Supported: HistInfo is not
present in the INVITE request.
NOTE 3. If information in the divertingLegInformation1 or
divertingLegInformation3 invoke indicates that privacy is required
for user CÆs number, then this will limit information that can be
provided in the History-Info header.
EDITORÆS NOTE. Progression of the History-Info I-D will need to be
monitored carefully to see how privacy is handled and how it
interacts with the privacy, P-Asserted-Identity and long-term
identity specifications. At present it looks as if it will be
necessary to suppress any History-Info header field that discloses
the identity of C in this situation and use existing rules concerning
P-Asserted-Identity.
NOTE 4. Until the divertingLegInformation3.inv arrives, the gateway
does not know whether privacy restrictions apply, and therefore
History-Info cannot be sent earlier. If divertingLegInformation3.inv
arrives before the CONNECT, History-Info may be sent in a provisional
response (e.g., in 180 or 181).
NOTE 5.If after sending a History-Info header in a provisional
response, a further divertingLegInformation1.inv arrives, a further
History-Info header can be sent subject to the rules above. This
header should contain all targeted-to-URIs to date, including that
derived from the latest divertingLegInformation1.inv.
Elwell et alia Expires - December 2003 [Page 19]
Interworking between SIP and QSIG June 2003
NOTE 6. Even if History-Info has been sent in a provisional response
and no further divertingLegInformation1.inv has been received, the
200 response should contain a History-Info header containing all
retargeted-to URIs.
NOTE 7. The diversionReason needs to be reflected in the History-Info
header. See section 9.4
10.2.2 Successful call û CFNR
+--------------+
IP network | Interworking | PISN
| unit |
+--------------+
||
INVITE req ||
Supported: HistInfo ||
--------------------------->||
|| QSIG SETUP
100 ||--------------------------->
<---------------------------||
|| QSIG CALL PROCEEDING
||<---------------------------
||
|| QSIG ALERTING
180 ||<---------------------------
<---------------------------||
||
|| QSIG FACILITY
||divertingLegInformation1.inv
||<---------------------------
|| QSIG CONNECT
200 ||divertingLegInformation3.inv
History-Info ||<---------------------------
<---------------------------||
||
Figure 6 û Example of scenario A2 (CFNR)
10.3 Scenario B1
Call from QSIG to SIP redirected back to QSIG network.
10.3.1 Successful diversion û CFU or CFB
+--------------+
PISN | Interworking | IP network
| unit |
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Interworking between SIP and QSIG June 2003
+--------------+
||
QSIG SETUP ||
--------------------------->||
||
QSIG CALL PROCEEDING || INVITE req
<---------------------------|| Supported: HistInfo
||--------------------------->
||
|| 100
||<---------------------------
||
|| 3xx
QSIG FACILITY ||<---------------------------
callRerouting.inv ||
<---------------------------||
||
QSIG FACILITY ||
callRerouting.res ||
--------------------------->||
||
QSIG DISCONNECT ||
--------------------------->||
||
QSIG RELEASE ||
<---------------------------||
||
QSIG RELEASE COMPLETE ||
--------------------------->||
||
Figure 7 û Example of scenario B1 (call forwarding unconditional or
call forwarding busy)
NOTE 1. This scenario applies only if the gateway does not act as a
rerouting proxy and issue a further INVITE request to the contact
URI(s) supplied. The decision to do this might be based on the value
of the contact URI(s). If the gateway acts as a rerouting proxy,
scenario A1 applies to the sending of diversion information towards
the calling user.
NOTE 2. For derivation of the reroutingReason in callRerouting.inv,
see section 9.3.
NOTE 3. The number in callRerouting.inv should be derived from the
Contact address header in the 3xx response. If there is more than one
contact address, one must be selected, e.g., the first one that can
be mapped to a number.
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Interworking between SIP and QSIG June 2003
NOTE 4. If the reroutingReason in callRerouting invoke indicates
CFNR, the QSIG DISCONNECT will not arrive until the diverted call has
been successfully established (alerting). The gateway should not
attempt to accelerate the clearing of the leg because that will cause
the QSIG rerouting PINX to clear the whole call.
NOTE 5. The subscriptionOption in the callRerouting.inv should
indicate no restriction, which means that user B has not requested
any restriction on providing diversion information to user A. If
privacy of this nature is required, SIP redirection is an
inappropriate mechanism.
10.3.2 Successful diversion û CFNR
+--------------+
PISN | Interworking | IP network
| unit |
+--------------+
||
QSIG SETUP ||
--------------------------->||
||
QSIG CALL PROCEEDING || INVITE req
<---------------------------|| Supported: HistInfo
||--------------------------->
||
|| 100
||<---------------------------
||
|| 180
QSIG ALERTING ||<---------------------------
<---------------------------||
|| 3xx
|| History-Info
QSIG FACILITY ||<---------------------------
callRerouting.inv ||
<---------------------------||
||
QSIG FACILITY ||
callRerouting.res ||
--------------------------->||
||
QSIG DISCONNECT ||
--------------------------->||
||
QSIG RELEASE ||
<---------------------------||
||
QSIG RELEASE COMPLETE ||
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Interworking between SIP and QSIG June 2003
--------------------------->||
||
Figure 8 û Example of scenario B1 (call forwarding no reply)
NOTE 1. For derivation of the diversionReason in callRerouting.inv,
see section 9.3.
NOTE 2. Because this is CFNR, the QSIG DISCONNECT will not arrive
until the diverted call has been successfully established (alerting).
The gateway should not attempt to accelerate the clearing of the leg
because that will cause the QSIG rerouting PINX to clear the whole
call.
NOTE 3. The subscriptionOption in the callRerouting.inv should
indicate no restriction.
10.3.3 Failure û callRerouting.err received
+--------------+
PISN | Interworking | IP network
| unit |
+--------------+
||
QSIG SETUP ||
--------------------------->||
||
QSIG CALL PROCEEDING || INVITE req
<---------------------------|| Supported: HistInfo
||--------------------------->
||
|| 100
||<---------------------------
||
|| 3xx
QSIG FACILITY ||<---------------------------
callRerouting.inv ||
<---------------------------||
||
QSIG FACILITY ||
callRerouting.err ||
--------------------------->||
||
QSIG DISCONNECT ||
<---------------------------||
||
QSIG RELEASE ||
--------------------------->||
||
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Interworking between SIP and QSIG June 2003
QSIG RELEASE COMPLETE ||
<---------------------------||
||
Figure 9 û Example of scenario B1 (call forwarding unconditional or
call forwarding busy)
NOTE 1. If callRerouting.err is received, the gateway may attempt to
take over the functions of the QSIG rerouting PINX. Otherwise it
should initiate clearing as shown.
10.3.4 Failure û No answer following CFNR
+--------------+
PISN | Interworking | IP network
| unit |
+--------------+
||
QSIG SETUP ||
--------------------------->||
||
QSIG CALL PROCEEDING || INVITE req
<---------------------------|| Supported: HistInfo
||--------------------------->
||
|| 100
||<---------------------------
||
|| 180
QSIG ALERTING ||<---------------------------
<---------------------------||
|| 3xx
|| History-Info
QSIG FACILITY ||<---------------------------
callRerouting.inv ||
<---------------------------||
||
QSIG FACILITY ||
callRerouting.res ||
--------------------------->||
||
QSIG FACILITY ||
cfnrDivertedLegFailed.inv ||
--------------------------->||
||
QSIG DISCONNECT ||
<---------------------------||
||
QSIG RELEASE ||
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Interworking between SIP and QSIG June 2003
--------------------------->||
||
QSIG RELEASE COMPLETE ||
<---------------------------||
||
Figure 10 û Example of scenario B1 (call forwarding no reply followed
by no answer)
NOTE 1. Because the reroutingReason in callRerouting invoke indicates
CFNR, a cfnrDivertedLegFailed invoke will arrive if diversion fails.
The QSIG expectation is that alerting will continue at B, but SIP
does not support this. Therefore the gateway will need to respond
with a QSIG DISCONNECT.
10.4 Scenario B2
Call from SIP to QSIG redirected back to SIP network.
10.4.1 Successful diversion
+--------------+
IP Network | Interworking | PISN
| unit |
+--------------+
INVITE req ||
Supported: HistInfo ||
-------------------------->||
||
100 ||
<---------------------------|| QSIG SETUP
||--------------------------->
||
|| QSIG CALL PROCEEDING
||<---------------------------
||
|| QSIG ALERTING
180 ||<---------------------------
<---------------------------||
|| QSIG FACILITY
|| callRerouting.inv
302 (Moved Temporarily)||<---------------------------
<---------------------------||
|| QSIG FACILITY
|| callRerouting.res
||--------------------------->
||
|| QSIG DISCONNECT
||--------------------------->
||
Elwell et alia Expires - December 2003 [Page 25]
Interworking between SIP and QSIG June 2003
|| QSIG RELEASE
||<---------------------------
||
|| QSIG RELEASE COMPLETE
||--------------------------->
||
Figure 11 û Example of scenario B2 (call forwarding no reply)
NOTE 1. This scenario applies only if the gateway does not act as the
rerouting PINX. This could be determined by configuration or on a
dynamic basis (e.g., depending on the value of calledAddress). If the
subscriptionOption in the callRerouting.inv indicates that
presentation of the diverted-to number to the calling user is
restricted, the gateway should act as the rerouting PINX. If the
gateway acts as the rerouting PINX, scenario A2 applies to the
sending of SIP history information towards the calling user.
NOTE 2. 302 (Moved Temporarily) seems to be the nearest 3xx match,
regardless of diversionReason.
NOTE 3. There appears to be no requirement to include History-Info in
the 302 response.
NOTE 4. The Contact header in the 302 response should be derived from
the number in the callRerouting.inv.
NOTE 5. This diagram illustrates CFNR, since callRerouting invoke
arrives after ALERTING. For CFNR, the rerouting PINX should wait to
see if diversion is successful, so that the call can continue to
alert B if not. There is no capability in SIP to indicate success or
failure of a 3xx response, and therefore the call to B has to be
cleared immediately (as for CFU and CFB).
10.5 Scenario C1
Call diverted in QSIG network to SIP network.
+--------------+
PISN | Interworking | IP network
| unit |
+--------------+
||
QSIG SETUP ||
divertingLegInformation2.inv||
--------------------------->||
|| INVITE req
QSIG CALL PROCEEDING || Supported: HistInfo
<---------------------------|| History-Info
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Interworking between SIP and QSIG June 2003
||--------------------------->
||
|| 100
||<---------------------------
||
|| 180
QSIG ALERTING ||<---------------------------
<---------------------------||
|| 200
|| History-Info
QSIG CONNECT ||<---------------------------
divertingLegInformation3.inv||
<---------------------------||
||
Figure 12 û Example of scenario C1
NOTE 1. If originalCalledNr and originalDiversionReason are absent,
two targeted-to URIs should be included in the History-Info header in
the INVITE request. The first is derived from the divertingNr
element. The second is derived from the diversionReason element and
the Request-URI. See section 9.4 for deriving SIP response codes for
inclusion in targeted-to URIs.
NOTE 2. If originalCalledNr and originalDiversionReason are present,
three targeted-to URIs should be included in the History-Info header
in the INVITE request. The first is derived from the
originalCalledNr element. The second is derived from the
originalDiversionReason element and the divertingNr element. The last
is derived from the diversionReason element and the Request-URI.
NOTE 3. Rules need to be established for setting the
presentationAllowedIndicator in divertingLegInformation3 invoke. It
might depend on the presence of History-Info, P-Asserted-Identity
and/or Privacy headers in the 200 response or provisional responses.
10.6 Scenario C2
Call diverted in SIP network to QSIG network.
+--------------+
IP Network | Interworking | PISN
| unit |
+--------------+
INVITE req ||
Supported: HistInfo ||
History-Info ||
-------------------------->||
||
Elwell et alia Expires - December 2003 [Page 27]
Interworking between SIP and QSIG June 2003
100 || QSIG SETUP
<---------------------------|| divertingLegInformation2.inv
||--------------------------->
||
|| QSIG CALL PROCEEDING
||<---------------------------
||
|| QSIG ALERTING
180 ||<---------------------------
<---------------------------||
|| QSIG CONNECT
200 || divertingLegInformation3.inv
History-Info ||<---------------------------
<---------------------------||
||
Figure 13 û Example of scenario C2
NOTE 1. divertingNr and diversionReason are derived from the
penultimate and last targeted-to-uri respectively in the History-Info
header. See section 9.3 for deriving diversionReason.
NOTE 2. originalCalledNr and originalDiversionReason are derived from
first and second targeted-to URI respectively in the History-Info
header if there are more than two present. Otherwise these elements
are omitted.
NOTE 3. The History-Info header may be sent earlier in a provisional
response (e.g, in 180 or 183). However, it must also be included in
the 200 response.
NOTE 4. Inclusion of History-Info in a response will depend on
privacy considerations, including presentationAllowed indicator in
divertingLegInformation3 invoke.
10.7 Scenario A1 followed by B1
+--------------+
PISN | Interworking | IP network
| unit |
+--------------+
||
QSIG SETUP ||
--------------------------->||
||
QSIG CALL PROCEEDING || INVITE req
<---------------------------|| Supported: HistInfo
||--------------------------->
||
Elwell et alia Expires - December 2003 [Page 28]
Interworking between SIP and QSIG June 2003
|| 100
||<---------------------------
||
|| 183
|| History-Info
QSIG PROGRESS ||<---------------------------
<---------------------------||
||
QSIG FACILITY ||
divertingLegInformation1.inv||
<---------------------------||
|| 3xx
QSIG FACILITY || History-Info
callRerouting.inv ||<---------------------------
<---------------------------||
||
QSIG FACILITY ||
callRerouting.res ||
--------------------------->||
||
QSIG DISCONNECT ||
--------------------------->||
||
QSIG RELEASE ||
<---------------------------||
||
QSIG RELEASE COMPLETE ||
--------------------------->||
||
Figure 14 û Example of scenario A1 followed by B1
NOTE 1. The sending of PROGRESS on receipt of a SIP 183 response is
dependent on the conditions specified in [9].
NOTE 2. The History-Info in the 3xx response reflects previous
retargets, not any retarget suggested by the 3xx response.
10.8 Scenario A2 followed by scenario B2
+--------------+
IP Network | Interworking | PISN
| unit |
+--------------+
INVITE req ||
Supported: HistInfo ||
-------------------------->||
||
100 ||
Elwell et alia Expires - December 2003 [Page 29]
Interworking between SIP and QSIG June 2003
<---------------------------|| QSIG SETUP
||--------------------------->
||
|| QSIG CALL PROCEEDING
||<---------------------------
||
|| QSIG FACILITY
||divertingLegInformation1.inv
||<---------------------------
||
|| QSIG FACILITY
|| callRerouting.inv
302 (Moved Temporarily)||<---------------------------
<---------------------------||
|| QSIG FACILITY
|| callRerouting.res
||--------------------------->
||
|| QSIG DISCONNECT
||--------------------------->
||
|| QSIG RELEASE
||<---------------------------
||
|| QSIG RELEASE COMPLETE
||--------------------------->
||
Figure 15 û Example of scenario A2 followed by B2
NOTE. No History-Info is sent back because no
divertingLegInformation3.inv has been received and therefore the
privacy situation is uncertain.
10.9 Scenario C1 followed by scenario A1
+--------------+
PISN | Interworking | IP network
| unit |
+--------------+
||
QSIG SETUP ||
divertingLegInformation2.inv||
--------------------------->||
|| INVITE req
QSIG CALL PROCEEDING || Supported: HistInfo
<---------------------------|| History-Info
||--------------------------->
||
Elwell et alia Expires - December 2003 [Page 30]
Interworking between SIP and QSIG June 2003
|| 100
||<---------------------------
||
|| 180
QSIG ALERTING ||<---------------------------
<---------------------------||
||
QSIG CONNECT || 200
divertingLegInformation1.inv|| History-Info
divertingLegInformation3.inv||<---------------------------
<---------------------------||
||
Figure 16 û Example of scenario C1 followed by A1
NOTE 1. This is similar to scenario C1 alone, except that scenario A1
applies for mapping History-Info in the 200 response (or a
provisional response) to information in the divertingLegInformation1
invoke. Care should be taken only to map information relating to
diversions in the IP network, not information derived from
divertingLegInformation2 invoke.
10.10 Scenario C2 followed by scenario A2
+--------------+
IP Network | Interworking | PISN
| unit |
+--------------+
INVITE req ||
Supported: HistInfo ||
History-Info ||
-------------------------->||
||
100 || QSIG SETUP
<---------------------------||divertingLegInformation2.inv
||--------------------------->
||
|| QSIG CALL PROCEEDING
||<---------------------------
||
|| QSIG FACILITY
||divertingLegInformation1.inv
||<---------------------------
||
|| QSIG ALERTING
180 ||<---------------------------
<---------------------------||
|| QSIG CONNECT
200 ||divertingLegInformation3.inv
Elwell et alia Expires - December 2003 [Page 31]
Interworking between SIP and QSIG June 2003
History-Info ||<---------------------------
<---------------------------||
||
Figure 17 û Example of scenario C2 followed by A2
NOTE 1. The History-Info header in the 200 response should reflect
both information from the History-Info header received in the INVITE
request and information derived from the
divertingLegInformation1.inv. However, if information in the
divertingLegInformation1 or divertingLegInformation3 invoke indicates
that privacy is required for user CÆs number, then this will limit
information that can be provided in the History-Info header.
10.11 Scenario C1 followed by scenario B1
+--------------+
PISN | Interworking | IP network
| unit |
+--------------+
||
QSIG SETUP ||
divertingLegInformation2.inv||
--------------------------->||
|| INVITE req
QSIG CALL PROCEEDING || Supported: HistInfo
<---------------------------|| History-Info
||--------------------------->
||
|| 100
||<---------------------------
||
|| 3xx
QSIG FACILITY || History-Info
callRerouting.inv ||<---------------------------
<---------------------------||
||
QSIG FACILITY ||
callRerouting.res ||
--------------------------->||
||
QSIG DISCONNECT ||
--------------------------->||
||
QSIG RELEASE ||
<----------------------------||
||
QSIG RELEASE COMPLETE ||
--------------------------->||
Elwell et alia Expires - December 2003 [Page 32]
Interworking between SIP and QSIG June 2003
||
Figure 18 û Example of scenario C1 followed by B1
10.12 Scenario C2 followed by scenario B2
+--------------+
IP Network | Interworking | PISN
| unit |
+--------------+
INVITE req ||
Supported: HistInfo ||
History-Info ||
-------------------------->||
||
100 || QSIG SETUP
<---------------------------||divertingLegInformation2.inv
||--------------------------->
||
|| QSIG CALL PROCEEDING
||<---------------------------
||
|| QSIG ALERTING
180 ||<---------------------------
<---------------------------||
|| QSIG FACILITY
302 (Moved Temporarily) || callRerouting.inv
History-Info ||<---------------------------
<---------------------------||
|| QSIG FACILITY
|| callRerouting.res
||--------------------------->
||
|| QSIG DISCONNECT
||--------------------------->
||
|| QSIG RELEASE
||<---------------------------
||
|| QSIG RELEASE COMPLETE
||--------------------------->
||
Figure 19 û Example of scenario C2 followed by B2
NOTE 1. The History-Info in the 302 response reflects that received
in the INVITE request.
Elwell et alia Expires - December 2003 [Page 33]
Interworking between SIP and QSIG June 2003
11 Security considerations
EDITOR'S NOTE. To be added
12 Author's Addresses
John Elwell
Siemens Communications
Technology Drive
Beeston
Nottingham, UK, NG9 1LA
email: john.elwell@siemens.com
Joanne McMillen
Avaya Inc.
1300 W. 120th Ave.
Westminster, CO 80234-2726
email: joanne@avaya.com
Olivier Rousseau
Alcatel Business Systems
32,Avenue Kleber
92700 Colombes
France
email: olivier.rousseau@col.bsf.alcatel.fr
Jean-Francois Rey
Alcatel Business Systems
8,Rue de Kervezennec, BP 82 802
29228 Brest Cedex 2
France
email: jean-francois.rey@bst.bsf.alcatel.fr
13 Normative References
[1] J. Rosenberg, H. Schulzrinne, et al., "SIP: Session initiation
protocol", RFC 3261.
[2] International Standard ISO/IEC 11572 "Private Integrated Services
Network - Circuit-mode Bearer Services - Inter-Exchange Signalling
Procedures and Protocol" (also published by ECMA as Standard
ECMA-143)
[3] International Standard ISO/IEC 11582 "Private Integrated Services
Network - Generic Functional Protocol for the Support of
Supplementary Services - Inter-Exchange Signalling Procedures and
Protocol" (also published by ECMA as Standard ECMA-165)
Elwell et alia Expires - December 2003 [Page 34]
Interworking between SIP and QSIG June 2003
[4] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[5] International Standard ISO/IEC 13872 "Private Integrated Services
Network û Specification, Functional Model and Information Flows û
Call Diversion Supplementary Services" (also published by ECMA as
Standard ECMA-173)
[6] International Standard ISO/IEC 13873 "Private Integrated Services
Network û Inter-Exchange Signalling Protocol û Call Diversion
Supplementary Services" (also published by ECMA as Standard ECMA-174)
[7] M. Barnes, M. Watson, C. Jennings, J. Peterson, "SIP Generic
Request History Information - Requirements", draft-ietf-sipping-req-
history-02 (work in progress)
[8] M. Barnes, M. Watson, C. Jennings, "An Extension to the Session
Initiation Protocol for Request History Information", draft-barnes-
sipping-history-info-02 (work in progress)
[9] F. Derks, J. Elwell, P. Mourot, O. Rousseau, "Interworking
between SIP and QSIG", draft-ietf-sipping-qsig2sip-02
[10] J. Postel, "Internet Protocol", RFC 791.
[11] S. Deering, R. Hinden, "Internet Protocol, Version 6 (IPv6)",
RFC 2460.
[12] J. Elwell, "User Identification in a SIP/QSIG Environment",
draft-elwell-sipping-identity-interworking-00 (work in progress)
Annex A (temporary) - Change log
Elwell et alia Expires - December 2003 [Page 35]
| PAFTECH AB 2003-2026 | 2026-04-24 00:11:41 |