Name: ETSI : ETSI TS 123 091 V15.0.0 (2018-07) - Digital cellular telecommunications system (Phase 2+) (GSM); Universal Mobile Telecommunications System (UMTS); Explicit Call Transfer (ECT) supplementary service; Stage 2 (3GPP TS 23.091 version 15.0.0 Release 15)
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RTS/TSGC-0423091vf00

General Information

Status

Published

Publication Date

02-Jul-2018

Technical Committee

3GPP CT 4 - MAP/CAMEL/GTP/BCH/SS/TrFO/IMS/GUP/WLAN (formely CN4)

Current Stage

12 - Completion

Completion Date

03-Jul-2018

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ETSI TS 123 091 V15.0.0 (2018-07) - Digital cellular telecommunications system (Phase 2+) (GSM); Universal Mobile Telecommunications System (UMTS); Explicit Call Transfer (ECT) supplementary service; Stage 2 (3GPP TS 23.091 version 15.0.0 Release 15)

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ETSI TS 123 091 V15.0.0 (2018-07)

ETSI TS 123 091 V15.0.0 (2018-07)
TECHNICAL SPECIFICATION
Digital cellular telecommunications system (Phase 2+) (GSM);
Universal Mobile Telecommunications System (UMTS);
Explicit Call Transfer (ECT) supplementary service;
Stage 2
(3GPP TS 23.091 version 15.0.0 Release 15)
GLOBAL SYSTEM FOR
MOBILE COMMUNICATIONS
---------------------- Page: 1 ----------------------
3GPP TS 23.091 version 15.0.0 Release 15 1 ETSI TS 123 091 V15.0.0 (2018-07)
Reference
RTS/TSGC-0423091vf00
Keywords
GSM,UMTS
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GSM and the GSM logo are trademarks registered and owned by the GSM Association.
ETSI
---------------------- Page: 2 ----------------------
3GPP TS 23.091 version 15.0.0 Release 15 2 ETSI TS 123 091 V15.0.0 (2018-07)
Intellectual Property Rights
Essential patents

IPRs essential or potentially essential to normative deliverables may have been declared to ETSI. The information

pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found

in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in

respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web

server (https://ipr.etsi.org/).

Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee

can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web

server) which are, or may be, or may become, essential to the present document.
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ETSI claims no ownership of these except for any which are indicated as being the property of ETSI, and conveys no

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Foreword

This Technical Specification (TS) has been produced by ETSI 3rd Generation Partnership Project (3GPP).

The present document may refer to technical specifications or reports using their 3GPP identities, UMTS identities or

GSM identities. These should be interpreted as being references to the corresponding ETSI deliverables.

The cross reference between GSM, UMTS, 3GPP and ETSI identities can be found under

http://webapp.etsi.org/key/queryform.asp.
Modal verbs terminology

In the present document "shall", "shall not", "should", "should not", "may", "need not", "will", "will not", "can" and

"cannot" are to be interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of

provisions).

"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.

ETSI
---------------------- Page: 3 ----------------------
3GPP TS 23.091 version 15.0.0 Release 15 3 ETSI TS 123 091 V15.0.0 (2018-07)
Contents

Intellectual Property Rights ................................................................................................................................ 2

Foreword ............................................................................................................................................................. 2

Modal verbs terminology .................................................................................................................................... 2

Foreword ............................................................................................................................................................. 4

1 Scope ........................................................................................................................................................ 5

2 References ................................................................................................................................................ 5

3 Definitions and abbreviations ................................................................................................................... 5

3.1 Definitions .......................................................................................................................................................... 5

3.2 Abbreviations ..................................................................................................................................................... 6

4 Explicit Call Transfer (ECT) .................................................................................................................... 6

4.1 Functions ............................................................................................................................................................ 6

4.2 SDL diagrams and information flows ................................................................................................................ 8

4.2.1 General description ....................................................................................................................................... 8

4.2.2 ECT (both calls answered) ............................................................................................................................ 8

4.2.3 ECT (one call answered, the other alerting) ............................................................................................... 11

4.3 Interaction with other supplementary services ................................................................................................. 14

4.3.1 Line Identification services ......................................................................................................................... 14

4.3.2 Call Forwarding Unconditional (CFU) ....................................................................................................... 16

4.3.3 Call Forwarding on mobile subscriber Busy (CFB) ................................................................................... 17

4.3.3.1 Call Forwarding on mobile subscriber Busy due to Network Determined User Busy (NDUB) ........... 17

4.3.3.2 Call Forwarding on mobile subscriber Busy due to User Determined User Busy (UDUB) ................. 17

4.3.4 Call Forwarding on No Reply (CFNRy) ..................................................................................................... 18

4.3.5 Call Forwarding on mobile subscriber Not Reachable (CFNRc)................................................................ 18

4.3.6 Call Waiting (CW) ...................................................................................................................................... 18

4.3.7 Call Hold (HOLD) ...................................................................................................................................... 18

4.3.8 Multi Party (MPTY) ................................................................................................................................... 18

4.3.9 Closed User Group (CUG) ......................................................................................................................... 18

4.3.10 Advice of Charge (AoC) services ............................................................................................................... 19

4.3.11 Call Barring services ................................................................................................................................... 19

4.3.12 Explicit Call Transfer (ECT) ...................................................................................................................... 19

4.4 Information stored in the HLR ......................................................................................................................... 19

4.5 State transition model ....................................................................................................................................... 19

4.6 Transfer of information from the HLR to the VLR .......................................................................................... 19

4.7 Information stored in the VLR ......................................................................................................................... 19

4.8 Handover .......................................................................................................................................................... 20

Annex A: Change history ..................................................................................................................... 21

History .............................................................................................................................................................. 22

ETSI
---------------------- Page: 4 ----------------------
3GPP TS 23.091 version 15.0.0 Release 15 4 ETSI TS 123 091 V15.0.0 (2018-07)
Foreword

This Technical Specification has been produced by the 3 Generation Partnership Project (3GPP).

The contents of the present document are subject to continuing work within the TSG and may change following formal

TSG approval. Should the TSG modify the contents of the present document, it will be re-released by the TSG with an

identifying change of release date and an increase in version number as follows:
Version x.y.z
where:
x the first digit:
1 presented to TSG for information;
2 presented to TSG for approval;
3 or greater indicates TSG approved document under change control.

y the second digit is incremented for all changes of substance, i.e. technical enhancements, corrections,

updates, etc.

z the third digit is incremented when editorial only changes have been incorporated in the document.

ETSI
---------------------- Page: 5 ----------------------
3GPP TS 23.091 version 15.0.0 Release 15 5 ETSI TS 123 091 V15.0.0 (2018-07)
1 Scope

The present document gives the stage 2 description of the call transfer supplementary services.

Only one call transfer supplementary service has been defined, this is the Explicit Call Transfer (ECT) supplementary

service, and is described in the present document.
2 References

The following documents contain provisions which, through reference in this text, constitute provisions of the present

document.

- References are either specific (identified by date of publication, edition number, version number, etc.) or

non-specific.
- For a specific reference, subsequent revisions do not apply.

- For a non-specific reference, the latest version applies. In the case of a reference to a 3GPP document (including

a GSM document), a non-specific reference implicitly refers to the latest version of that document in the same

Release as the present document.
[1] 3GPP TR 21.905: "3G Vocabulary".

[2] 3GPP TS 23.083: "Call Waiting (CW) and Call Hold (HOLD) supplementary services - Stage 2".

[3] 3GPP TS 24.008: "Mobile Radio Interface Layer 3 specification; Core Network Protocols - Stage

3".

[4] EN 300 368: "Integrated Services Digital network (ISDN); Explicit Call Transfer (ECT)

supplementary service; Functional capabilities and information flows".

[5] EN 300 356-14: "Integrated Services Digital network (ISDN); Signalling System No. 7; ISDN

User Part (ISUP) version 3 for the international interface; Part 14: Explicit Call Transfer (ECT)

supplementary service ".
[6] 3GPP TS 23.011: "Technical realization of Supplementary Services".
[7] 3GPP TS 23.018: "Basic Call Handling".
3 Definitions and abbreviations
3.1 Definitions
First call: One of the subscriber A calls (answered).

Notification Indicator (NI): Indicates to each remote party in which state of the other remote party ECT was

performed (active, alerting).

Redirection Number (Rdn): Includes the presentation indicator and the directory number of the other remote party.

Second call: The other subscriber A call (answered or alerting).

Subscriber A (PARTY A): The served mobile subscriber - the one who has subscribed to, and invokes the ECT

Supplementary Service.
Subscriber B (PARTY B): The other party in the subscriber A first call.
Subscriber C (PARTY C): The other party in the subscriber A second call.

Subscriber D (PARTY D): The forwarded-to party when the call is forwarded by the subscriber C.

Transferred call: The resulting call after successful explicit call transfer between B and C.

ETSI
---------------------- Page: 6 ----------------------
3GPP TS 23.091 version 15.0.0 Release 15 6 ETSI TS 123 091 V15.0.0 (2018-07)
3.2 Abbreviations

In addition to those below, abbreviations used in the present document are listed in 3GPP TR 21.905 [1].

ECT: Explicit Call Transfer supplementary service
LI: Line Identity
NI: Notification Indicator
Rdn: Redirection number
RdnB: Redirection number of party B
RdnD: Redirection number of party D
4 Explicit Call Transfer (ECT)
4.1 Functions

The following function has been identified for the explicit call transfer service:

MAF027
Explicit Call Transfer related authorizations examination

The ability of a PLMN component to determine the authorizations relating to explicit call transfer. See figure

Location: VLR
ETSI
---------------------- Page: 7 ----------------------
3GPP TS 23.091 version 15.0.0 Release 15 7 ETSI TS 123 091 V15.0.0 (2018-07)
Process MAF027 391_1(1)
Process in the VLR to check Signals to/from the left are
if ECT is provisioned. to/from the MSC.
Idle
Check ECT
subscription
ECT
provisioned
Yes
SS-CSI
provisioned?
Yes
ECT marked
in CSI?
Yes
Indicator:= Indicator:=
Indicator:=
ECT_available ECT_not_
ECT_available
+ SS-CSI available
Process
ECT
Idle
Figure 1: Explicit Call Transfer related authorizations examination (VLR)
ETSI
---------------------- Page: 8 ----------------------
3GPP TS 23.091 version 15.0.0 Release 15 8 ETSI TS 123 091 V15.0.0 (2018-07)
4.2 SDL diagrams and information flows
4.2.1 General description

The procedures Handle_ECT_Active and Handle_ECT_Alerting show the behaviour of the service as perceived by the

served mobile subscriber and by any of the other parties involved in the transfer. These procedures and the macro

Check_ECT show the actions to be taken by the network and the information provided by the network to the users.

The following states for the invocation of the ECT supplementary service are defined:

a) First Call (Active, Held), Second Call (Active, Idle);
b) First Call (Active, Held), Second Call (Call Delivered, Idle).

NOTE: The call state "call delivered" means that an ALERTING message has been sent to the MS, but no

ANSWER Message (ANM) has been received.

In the information flows it is assumed that the served subscriber is a mobile subscriber and that the other parties are

mobile or fixed subscribers.

Party A is the subscriber controlling the Explicit Call Transfer Call (served mobile subscriber). Party B is the first

remote party called. Party C is the second remote party called.

The served party is disconnected by the generic disconnect/release procedure after a successful transfer request. The

connection of the remote parties in a new call (transferred call) is located in the served subscriber's MSC.

The information flows in figures 4 and 7 show the unsuccessful case (i.e. the check in the VLR or in the MSC fails).

The information flows in figures 5 and 8 show the successful case.
4.2.2 ECT (both calls answered)

The SDL for the procedure Handle_ECT_Active (Explicit Call Transfer - both calls have been answered) is shown in

figure 2.

The checks of whether Explicit Call Transfer is barred or not are shown in figure 3.

The corresponding information flows are given in figure 4 and figure 5.
ETSI
---------------------- Page: 9 ----------------------
3GPP TS 23.091 version 15.0.0 Release 15 9 ETSI TS 123 091 V15.0.0 (2018-07)
Procedure Handle_ECT_Active ECT_Ac(1)
Procedure in the originating MSC to handle Signals to/from the left are
an Explicit Call Transfer when the first call leg to/from the MS;
(A-B) is connected and on hold and the other signals to/from the right are
call leg (A-C) is connected and active. to/from all/any remote parties
unless stated otherwise.
Check_ECT
Pass Fail
Connect both ECT
calls reject
Retrieve
To the held party Result:=Fail
notification
Transfer
notification
ECT ack
Yes
SS-CSI
present?
SS Invocation
To gsmSCF
notify
For call legs Disconnect
A-B & A-C request
Result:=Pass
Figure 2: Procedure Handle_ECT_Active
ETSI
---------------------- Page: 10 ----------------------
3GPP TS 23.091 version 15.0.0 Release 15 10 ETSI TS 123 091 V15.0.0 (2018-07)
Macrodefinition Check_ECT 1(1)
Macro in the originating MSC to check if
an Explicit Call Transfer can be performed.
ECT Treatment Indicator
present in SII2 (for
either ongoing call)?
Yes
ECT Treatment Indicator
set to Reject ECT request
Yes
(for either ongoing call)?
Check ECT
subscription
Wait_For_
ECT_Status_
Reply
Process Int_Release_ Release
Release
ECT Call transaction
From distant
From gsmSSF From BSS
exchange
ECT
activ e?
Yes
Yes
Transfer barred by
SS interaction?
Loop
Prev ention
Yes
procedure
Loop check?
Failure Success
Fail Pass
Figure 3: Macro Check_ECT
ETSI
---------------------- Page: 11 ----------------------
3GPP TS 23.091 version 15.0.0 Release 15 11 ETSI TS 123 091 V15.0.0 (2018-07)

MSa MSCa VLRa MSCb MSb LEc TEcá

┌──┐ ┌──┐ ┌──┐ ┌──┐ ┌──┐ ┌──┐ ┌──┐

│ A-B (active, held) / A-C (active, idle) │ │ │ │ │ │ │ │

│ ───────────────────────────────────────── │ │ │ │ │ │ │ │

│ │ │ │ │ │ │ │ │ │ │ │ │ │

│ │ ECT request │ │ │ │ │ │ │ │ │ │ │ │

│ │ ─────────────> │ │info request │ │ │ │ │ │ │ │ │ │

│ │ │ │ ─────────> │ │ │ │ │ │ │ │ │ │

│ │ │ │ │MAF027 │ │ │ │ │ │ │ │

│ │ │ │ info ack │ │ │ │ │ │ │ │ │ │

│ │ │ │ < ───────── │ │ │ │ │ │ │ │ │ │

│ │ │OR1:N │ │ │ │ │ │ │ │ │ │

│ │ ECT rej │ │ │ │ │ │ │ │ │ │ │ │

│ │ < ───────────── │ │ │ │ │ │ │ │ │ │ │ │

│ │ │ │ │ │ │ │ │ │ │ │ │ │

│ A-B (active, held) / A-C (active, idle) │ │ │ │ │ │ │ │

│ ───────────────────────────────────────── │ │ │ │ │ │ │ │

│ │ │ │ │ │ │ │ │ │ │ │ │ │

NOTE: OR1: Checks in VLR and MSC ok? (Y: yes N: no).

Figure 4: Information flow for failed explicit call transfer request (both calls answered)

MSa MSCa VLRa MSCb MSb LEc TEc

┌──┐ ┌──┐ ┌──┐ ┌──┐ ┌──┐ ┌──┐ ┌──┐

│ A-B (active, held) / A-C (active, idle) │ │ │ │ │ │ │ │

│ ───────────────────────────────────────── │ │ │ │ │ │ │ │

│ │ │ │ │ │ │ │ │ │ │ │ │ │

│ │ ECT request │ │ │ │ │ │ │ │ │ │ │ │

│ │ ─────────────> │ │info request │ │ │ │ │ │ │ │ │ │

│ │ │ │ ─────────> │ │ │ │ │ │ │ │ │ │

│ │ │ │ │MAF027 │ │ │ │ │ │ │ │

│ │ │ │ info ack │ │ │ │ │ │ │ │ │ │

│ │ │ │ < ───────── │ │ │ │ │ │ │ │ │ │

│ │ │OR1:Y │ │ │ │ │ │ │ │ │ │

│ │ │ │ │ │ │ │ │ │ │ │ │ │

│ │ connect calls │ │ │ │ │ │ │ │ │ │

│ │ │ │ │ │ │ │ │ │ │ │ │ │

│ │ │ │ notification (retrieve) │ │ │ │ │ │ │ │

│ │ │ │ ───────────────────────> │ │notification (retr) │ │ │ │ │

│ │ │ │ │ │ │ │ ─────────────> │ │ │ │ │ │

│ │ │ │ notification (ECT) │ │ │ │ │ │ │ │

│ │ │ │ ───────────────────────> │ │notification (ECT) │ │ │ │ │

│ │ │ │ (active, Rdn) │ │ ─────────────> │ │ │ │ │ │

│ │ │ │ │ │ │ │ (active, Rdn) │ │ │ │ │ │

│ │ │ │ │ │ │ │ │ │ │ │ │ │

│ │ │ │ notification (ECT) │ │ │ │ │ │ │ │

│ │ │ │ ─────────────────────────────────────────────────────────> │ │ notification(ECT) │

│ │ │ │ (active, Rdn) │ │ │ │ │ │ ────────────> │ │

│ │ │ │ │ │ │ │ │ │ │ │ (active, Rdn) │ │

│ │ ECT ack │ │ │ │ │ │ │ │ │ │ │ │

│ │ < ───────────── │ │ │ │ │ │ │ │ │ │ │ │

│ │ disc req A-B │ │ │ │ │ │ │ │ │ │ │ │

│ │ < ───────────── │ │ │ │ │ │ │ │ │ │ │ │

│ │ NORMAL DISCONNECTION A-B │ │ │ │ │ │ │ │ │ │

│ │ │ │ │ │ │ │ │ │ │ │ │ │

│ │ disc req A-C │ │ │ │ │ │ │ │ │ │ │ │

│ │ < ───────────── │ │ │ │ │ │ │ │ │ │ │ │

│ │ NORMAL DISCONNECTION A-C │ │ │ │ │ │ │ │ │ │

│ │ │ │ │ │ │ │ │ │ │ │ │ │

│ B-C (active, idle) │ │ │ │ │ │ │ │ │ │ │

│ ──────────────────── │ │ │ │ │ │ │ │ │ │ │

│ │ │ │ │ │ │ │ │ │ │ │ │ │

NOTE: OR1: Checks in VLR and MSC ok? (Y: yes N: no).

Figure 5: Information flow for successful explicit call transfer (both calls answered)

4.2.3 ECT (one call answered, the other alerting)

The SDL for the procedure Handle_ECT_Alerting (Explicit Call Transfer - one call answered, the other alerting) is

shown in figure 6.

The checks of whether Explicit Call Transfer is barred or not are shown in figure 3.

ETSI
---------------------- Page: 12 ----------------------
3GPP TS 23.091 version 15.0.0 Release 15 12 ETSI TS 123 091 V15.0.0 (2018-07)
The corresponding information flows are given in figure 7 and figure 8.
Procedure Handle_ECT_Alerting ECT_Al(1)
Procedure in the originating MSC to handle Signals to/from the left are
an Explicit Call Transfer when the first call leg to/from the MS;
(A-B) is connected and on hold and the other signals to/from the right are
call leg (A-C) is connected and alerting. to/from all/any remote parties
unless stated otherwise.
False
Alerting
True
Check_ECT
Pass Fail
Connect both ECT
calls reject
Retrieve
To the held party Result:=Fail
notification
ECT
notification
ECT ack
Yes
SS-CSI
present?
SS Invocation
To gsmSCF
notify
Disconnect For call legs
request A-B & A-C
Result:=Pass
Figure 6: Procedure Handle_ECT_Alerting
ETSI
---------------------- Page: 13 ----------------------
3GPP TS 23.091 version 15.0.0 Release 15 13 ETSI TS 123 091 V15.0.0 (2018-07)

MSa MSCa VLRa MSCb MSb LEc TEc

┌──┐ ┌──┐ ┌──┐ ┌──┐ ┌──┐ ┌──┐ ┌──┐

│ A-B (active, held) / A-C (call delivered, idle) │ │ │ │ │ │ │ │

│ ───────────────────────────────────────────────── │ │ │ │ │ │ │

│ │ │ │ │ │ │ │ │ │ │ │ │ │

│ │ ECT request │ │ │ │ │ │ │ │ │ │ │ │

│ │ ─────────────> │ │info request │ │ │ │ │ │ │ │ │ │

│ │ │ │ ─────────> │ │ │ │ │ │ │ │ │ │

│ │ │ │ │MAF027 │ │ │ │ │ │ │ │

│ │ │ │ info ack │ │ │ │ │ │ │ │ │ │

│ │ │ │ < ───────── │ │ │ │ │ │ │ │ │ │

│ │ │OR1:N │ │ │ │ │ │ │ │ │ │

│ │ ECT rej │ │ │ │ │ │ │ │ │ │ │ │

│ │ < ───────────── │ │ │ │ │ │ │ │ │ │ │ │

│ │ │ │ │ │ │ │ │ │ │ │ │ │

│ A-B (active, held) / A-C (call delivered, idle) │ │ │ │ │ │ │ │

│ ─────────────────────────────────────────────── │ │ │ │ │ │ │ │

│ │ │ │ │ │ │ │ │ │ │ │ │ │

NOTE: OR1: Checks in VLR and MSC ok? (Y: yes N: no).
Figure 7: Information flow for failed explicit call transfer request
(one call answered, the other alerting)
ETSI
---------------------- Page: 14 ----------------------
3GPP TS 23.091 version 15.0.0 Release 15 14 ETSI TS 123 091 V15.0.0 (2018-07)

MSa MSCa VLRa MSCb MSb LEc TEc

┌──┐ ┌──┐ ┌──┐ ┌──┐ ┌──┐ ┌──┐ ┌──┐

│ A-B (active, held) / A-C (call delivered, idle) │ │ │ │ │ │ │ │

│ ──────────────────────────
...

ETSI TS 123 091 V15.0.0 (2018-07)

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