ETSI TS 132 281 V16.1.0 (2020-11)

Universal Mobile Telecommunications System (UMTS); LTE; Telecommunication management; Charging management; Announcement service (3GPP TS 32.281 version 16.1.0 Release 16)

RTS/TSGS-0532281vg10

General Information

• Status: Not Published
• Technical Committee: 3GPP SA 5 - Telecom Management
• Current Stage: 12 - Completion
• Completion Date: 17-Nov-2020

Standards Content (Sample)

TECHNICAL SPECIFICATION
Universal Mobile Telecommunications System (UMTS);
LTE;
Telecommunication management;
Charging management;
Announcement service
(3GPP TS 32.281 version 16.1.0 Release 16)

3GPP TS 32.281 version 16.1.0 Release 16 1 ETSI TS 132 281 V16.1.0 (2020-11)

Reference
RTS/TSGS-0532281vg10
Keywords
LTE,UMTS
ETSI
650 Route des Lucioles
F-06921 Sophia Antipolis Cedex - FRANCE

Tel.: [phone]  Fax: [phone]

Siret N° 348 623 562 00017 - NAF 742 C
Association à but non lucratif enregistrée à la
Sous-Préfecture de Grasse (06) N° 7803/88

Important notice
The present document can be downloaded from:
http://www.etsi.org/standards-search
The present document may be made available in electronic versions and/or in print. The content of any electronic and/or
print versions of the present document shall not be modified without the prior written authorization of ETSI. In case of any
existing or perceived difference in contents between such versions and/or in print, the prevailing version of an ETSI
deliverable is the one made publicly available in PDF format at www.etsi.org/deliver.
Users of the present document should be aware that the document may be subject to revision or change of status.
Information on the current status of this and other ETSI documents is available at
https://portal.etsi.org/TB/ETSIDeliverableStatus.aspx
If you find errors in the present document, please send your comment to one of the following services:
https://portal.etsi.org/People/CommiteeSupportStaff.aspx
Copyright Notification
No part may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying
and microfilm except as authorized by written permission of ETSI.
The content of the PDF version shall not be modified without the written authorization of ETSI.
The copyright and the foregoing restriction extend to reproduction in all media.

© ETSI 2020.
All rights reserved.
DECT™, PLUGTESTS™, UMTS™ and the ETSI logo are trademarks of ETSI registered for the benefit of its Members.

3GPP™ and LTE™ are trademarks of ETSI registered for the benefit of its Members and
of the 3GPP Organizational Partners.
oneM2M™ logo is a trademark of ETSI registered for the benefit of its Members and
of the oneM2M Partners. ®
GSM and the GSM logo are trademarks registered and owned by the GSM Association.
ETSI
3GPP TS 32.281 version 16.1.0 Release 16 2 ETSI TS 132 281 V16.1.0 (2020-11)
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.
Trademarks
The present document may include trademarks and/or tradenames which are asserted and/or registered by their owners.
ETSI claims no ownership of these except for any which are indicated as being the property of ETSI, and conveys no
right to use or reproduce any trademark and/or tradename. Mention of those trademarks in the present document does
not constitute an endorsement by ETSI of products, services or organizations associated with those trademarks.
Legal Notice
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. These shall be
interpreted as being references to the corresponding ETSI deliverables.
The cross reference between 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
3GPP TS 32.281 version 16.1.0 Release 16 3 ETSI TS 132 281 V16.1.0 (2020-11)
Contents
Intellectual Property Rights . 2
Legal Notice . 2
Modal verbs terminology . 2
Foreword . 4
1 Scope . 5
2 References . 6
3 Definitions, symbols and abbreviations . 7
3.1 Definitions . 7
3.2 Symbols . 7
3.3 Abbreviations . 7
4 Architecture considerations . 9
4.1 High level Announcement aspects . 9
4.2 Announcement in IP Multimedia Subsystem (IMS) architecture . 9
5 Announcement principles and flows . 10
5.1 Common announcement principles . 10
5.2 Announcement in IMS . 10
5.2.1 Basic principles and definitions . 10
5.2.2 Message flows and types for online charging . 11
5.2.3 Message flows and types for converged charging . 22
Scenario 1: Immediate announcement at start of session with establishment . 23
Scenario 2: Immediate announcement at start of session with termination . 25
Scenario 3: Deferred announcement in session with continuation . 27
Scenario 4: Deferred an announcement in session with session termination . 28
6 Definition of Announcement Information . 30
6.1 Announcement Information principles . 30
6.2 Announcement data definition . 31
6.2.1 Multiple Unit Operation contents for Announcement service . 31
6.2.2 Definition of Announcement Information . 31
6.2.3 Formal Announcement Information parameter description . 31
6.3 Bindings for Announcement Information . 31
Annex A (informative): Change history . 33
History . 34

ETSI
3GPP TS 32.281 version 16.1.0 Release 16 4 ETSI TS 132 281 V16.1.0 (2020-11)
Foreword
rd
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
3GPP TS 32.281 version 16.1.0 Release 16 5 ETSI TS 132 281 V16.1.0 (2020-11)
1 Scope
During any phase of a voice or video call, the Online Charging System (OCS) may need to deliver billing/charging in-
session notifications to the end user via announcements as part of the rating, balance management and billing process.
For example, the OCS may need to inform the user about usage states, threshold crossings, offer statuses, reason for call
rejection, alerts about low balances, etc.
In Circuit Switched (CS) domain, online charging of a voice session is performed using Customised Applications for
Mobile network Enhanced Logic (CAMEL) mechanisms. In order to deliver in-session notifications or to interact with
the end user, OCS can use CAMEL messages such as: Play Announcement, Prompt and Collect, Connect to Resource,
Establish Temporary Connection. Such notifications can be delivered pre-, mid- or post-call. However, in IMS and
MMTel charging defined in TS 32.260 [20] and TS 32.275 [35] as well as in Diameter Credit-Control Application
(DCCA) defined in RFC 4006 [402], announcement capabilities, available at the OCS level, are limited to redirection of
a session to a given SIP URI at completion of the session. When redirected the session may be connected to a resource
that delivers an announcement.
The Announcement service in this specification provides announcement capabilities for use in a Diameter based online
charging session. The OCS is able to specify that a given announcement be played to a call party in order to deliver
charging/billing related notifications.
ETSI
3GPP TS 32.281 version 16.1.0 Release 16 6 ETSI TS 132 281 V16.1.0 (2020-11)
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 TS 32.240: "Telecommunication management; Charging management; Charging
Architecture and Principles".
[2] – [9] Void
[10] 3GPP TS 32.250: "Telecommunication management; Charging management; Circuit Switched
(CS) domain charging".
[11] – [19] Void
[20] 3GPP TS 32.260: "Telecommunication management; Charging management; IP Multimedia
Subsystem (IMS) charging".
[21] – [29] void
[30] 3GPP TS 32.270: "Telecommunication management; Charging management; Multimedia
Messaging Service (MMS) charging".
[31] - [34] void
[35] 3GPP TS 32.275: "Telecommunication management; Charging management; MultiMedia
Telephony (MMTel) charging".
[36] - [49] Void
[50] 3GPP TS 32.299: "Telecommunication management; Charging management; Diameter charging
application".
[51] - [99] Void
[100] 3GPP TR 21.905: "Vocabulary for 3GPP Specifications".
[101] 3GPP TS 22.115: "Service aspects; Charging and billing".
[102] - [200] Void.
[201] -[203] Void.
[204] 3GPP TS 24.229: "IP multimedia call control protocol based on Session Initiation Protocol (SIP)
and Session Description Protocol (SDP); Stage 3".
[205] - [243] Void.
[244] 3GPP TS 24.628: "Common Basic Communication procedures using IP Multimedia (IM) Core
Network (CN) subsystem; Protocol specification".
[245] - [299] Void.
[300] - [401] Void.
[402] IETF RFC 4006 (2005): "Diameter Credit-Control Application".
ETSI
3GPP TS 32.281 version 16.1.0 Release 16 7 ETSI TS 132 281 V16.1.0 (2020-11)

3 Definitions, symbols and abbreviations
3.1 Definitions
For the purposes of the present document, the terms and definitions given in TR 21.905 [100] and the following apply.
A term defined in the present document takes precedence over the definition of the same term, if any, in
TR 21.905 [100].
CAMEL: network feature that provides the mechanisms to support operator specific services even when roaming
outside HPLMN.
circuit switched domain: domain within GSM / UMTS in which information is transferred in circuit switched mode.
Credit-Control: mechanism which directly interacts in real-time with an account and controls or monitors the charges,
related to the service usage. Credit-Control is a process of: checking if credit is available, credit reservation, deduction
of credit from the end user account when service is completed and refunding of reserved credit not used.
online charging: charging mechanism where charging information can affect, in real-time, the service rendered and
therefore a direct interaction of the charging mechanism with bearer/session/service control is required.
Online Charging System: the entity that performs real-time Credit-Control. Its functionality includes transaction
handling, rating, online correlation and management of subscriber accounts/balances.
3.2 Symbols
For the purposes of the present document, the following symbols apply:
Symbol format
Cr Reference Point between an AS and an MRFC for media control.
ISC Reference Point between a CSCF and an Application Server and between a CSCF and an MRB.
Mp Reference Point between an MRFC and an MRFP.
Mr Reference Point between an CSCF and an MRFC.
Mr ′ Reference Point between an AS and an MRFC for session control.
Ro Online Charging Reference Point between an AS, MRFC or the IMS-GWF and the OCS
3.3 Abbreviations
For the purposes of the present document, the abbreviations given in TR 21.905 [100] and the following apply.
An abbreviation defined in the present document takes precedence over the definition of the same abbreviation, if any,
in TR 21.905 [100].
AS Application Server
CAMEL Customised Applications for Mobile network Enhanced Logic
CCA Credit-Control-Answer
CCR Credit-Control-Request
CS Circuit Switched
CSCF Call Session Control Function (I-Interrogating; P-Proxy; and S-Serving)
DCCA Diameter Credit-Control Application

IMS-GWF IMS Gateway Function
ISC IMS Service Control
MMTel MultiMedia Telephony
MRB Media Resource Broker
MRFC Media Resource Function Controller
MRFP Multimedia Resource Function Processor
OCS Online Charging System
SIP Session Initiation Protocol
ETSI
3GPP TS 32.281 version 16.1.0 Release 16 8 ETSI TS 132 281 V16.1.0 (2020-11)
UE User Equipment
ETSI
3GPP TS 32.281 version 16.1.0 Release 16 9 ETSI TS 132 281 V16.1.0 (2020-11)
4 Architecture considerations
4.1 High level Announcement aspects
Each technology to which the Announcement service is applied will utilize a technology-specific special resource
function to play announcement media. Each of the architectures described in this clause utilizes the common
Announcement service specified in this document.
4.2 Announcement in IP Multimedia Subsystem (IMS)
architecture
The MRFC/MRFP are resources of the IMS that provide support for bearer related services such as announcements.
Collectively, the MRFC/MRFP is known as the Media Resource Function. The architecture of MRF is shown in figure
4.2.1.
AS
Cr
ISC
Mr ′
Mr
MRFC
S-CSCF
Mp
MRFP
Figure 4.2.1: Architecture of Media Resource Function in IMS
In the IMS online and converged charging architecture specified in TS 32.260 [20], both the AS and the IMS-GWF
interfaces the CHF/OCS. Either the AS or the IMS-GWF may utilize the Announcement service specified in this
document.
ETSI
3GPP TS 32.281 version 16.1.0 Release 16 10 ETSI TS 132 281 V16.1.0 (2020-11)
5 Announcement principles and flows
5.1 Common announcement principles
The CHF/OCS may provide information in charging messages that describe announcements to be played to a
subscriber. When receiving announcement information provided by the CHF/OCS, the receiving node shall use the
procedures defined for the specific technology in use. The clauses that follow identify the principles and message flows
applicable to each specific technology to which the common Announcement service is applied.
5.2 Announcement in IMS
5.2.1 Basic principles and definitions
The CHF/OCS may provide information in charging messages that describe video or audio announcements which can
be rendered to a subscriber involved in an IMS session at different stages of interactions with CHF/OCS.
When receiving announcement information provided by CHF/OCS, the AS or the IMS-GWF shall use the procedures
defined in clause 10.2.2 of TS 24.229 [204] and TS 24.628 [244] in order to deliver the required announcement in
accordance with the provided announcement information.
CHF/OCS can provide announcement information upon interaction with the AS or the IMS-GWF, during different
phases of an IMS session:
- At IMS session initiation, before the IMS session is allowed to continue and no quota is granted, or before the
IMS session is allowed to continue and use granted quota;
- During an ongoing established IMS session, with media components between the parties of the session, on quota
allocation control process;
- At an IMS session termination due to final quota consumption.
Announcements provided by CHF/OCS are driven by quota allocation during the IMS session, and controlled by an
indication on when they shall be played:
- Pre-quota announcement shall be played prior to any quota consumption (i.e. immediately);
- Mid-quota announcements shall be played at a specified duration before granted quota is exhausted, which
ranges from non-zero value smaller than the granted quota.
- Post-quota announcements shall be played upon granted quota exhaustion
CHF/OCS can provide information for one or more announcements in the same charging message.
A CHF/OCS-provided announcement is delivered to a single party of an IMS session. CHF/OCS indicates to which
party the announcement shall be played. This can be the served party or the remote party. When the privacy indicator
for the announcement is set to "private", the announcement shall be played only to the requested party. The handling
toward the other party during announcement playback is determined by the AS or the IMS-GWF internal logic.
The AS or the IMS-GWF shall control delivery of the announcements based on the announcement content information
provided by the CHF/OCS. The AS or the IMS-GWF shall use the procedures in TS 24.628 [244] for announcement
delivery. When the AS or the IMS-GWF are separate from the MRFC, the AS or the IMS-GWF shall support one or
more of the control methods for announcement referenced in clause 10.2.2 of TS 24.229 [204], regardless of the
announcement content information provided by the CHF/OCS. The AS or the IMS-GWF is responsible for determining
the MRF handling the announcement.
Announcement information indicates whether any of the granted quota shall be used by the AS or the IMS-GWF during
the time the announcement is connected. If not explicitly indicated in the announcement information by the CHF/OCS,
it is up to the service logic implemented in the AS or the IMS-GWF to use or not the granted quota.
For announcements delivered by the AS or the IMS-GWF during an IMS established session, the existing media shall
be suspended while the announcement media is played.
ETSI
3GPP TS 32.281 version 16.1.0 Release 16 11 ETSI TS 132 281 V16.1.0 (2020-11)
5.2.2 Message flows and types for online charging
The following figures show the Reserve Units transactions that are required between the IMS-GWF/AS and the OCS
for session-related IMS procedures when the Announcement service is invoked.
The SIP messages and Charging Data transactions associated with these charging scenarios are shown primarily for
general information and to illustrate the charging triggers. They are not intended to be exhaustive and they depend on
the Reserve Units Request triggers configured by the operator.
All of the scenarios depict originating sessions only.
Scenario 1: Pre-quota announcement with successful session establishment
Figure 5.2.2.1 shows the Reserve Units transactions that are required in the IMS-GWF/AS during a SIP session
establishment for which a pre-quota announcement is requested with successful session establishment.
IMS-GWF
S-CSCF OCS MRFC/MRFP
/ AS
1. INVITE 1. INVITE
Service control
2. Reserve Units Request[Initial]
Credit control
3. Reserve Units Response[Initial]
3a. Establish SIP session between calling party and MRFC/MRFP as per TS 24.628 [244] and TS 24.229 [204].
3b. Announcement playback
3c. Disconnect SIP session with the MRFC/MRFP as per TS 24.628 [244] and TS 24.229 [204].
4. INVITE
4. INVITE
More SIP signalling and optionally more Reserve Unit Requests
5. 200 OK (Invite)
5. 200 OK (Invite)
Service control
6. Reserve Units Request[Update]
Credit control
7. Reserve Units Response[Update]
8. 200 OK (Invite)
8. 200 OK (Invite)
Figure 5.2.2.1: Message sequence chart for pre-quota announcement with successful session
establishment
ETSI
3GPP TS 32.281 version 16.1.0 Release 16 12 ETSI TS 132 281 V16.1.0 (2020-11)
1) An initial SIP Invite Request is received in the S-CSCF. This request is forwarded to the IMS-GWF/AS.
2) The IMS-GWF/AS sends a Reserve Units Request[Initial] to the OCS requesting service units. The online
Credit-Control session is initiated.
3) The OCS grants units in a Multiple Unit Operation of the Reserve Units Response with a successful Operation
Result and requests an announcement to be played to the calling party immediately. Announcement information
may indicate whether or not the granted quota for the IMS session shall be used for playing the announcement.
3a) The IMS-GWF/AS establishes a SIP session between the calling party and an MRFC/MRFP for the requested
announcement as per TS 24.628 [244] and TS 24.229 [204].
3b) The MRFP plays the announcement to the calling party.
3c) When the announcement is complete, the IMS-GWF/AS disconnects the SIP session with the MRFC/MRFP as
per TS 24.628 [244] and TS 24.229 [204].
4) The IMS-GWF/AS and S-CSCF forward the initial SIP INVITE.
5) A final response is received in the IMS-GWF/AS.
6) If the trigger is active, the SIP 200 OK answer triggers a Reserve Units Request[Update] in the IMS-GWF/AS in
order to update the Credit-Control session. New service units are requested in a Multiple Unit Operation. Also
the used service units (if any) are reported in the Multiple Unit Operation. If the indication in step 3 is to use the
granted quota then the quota usage allocated for playing the announcement shall be reported by the IMS-
GWF/AS to the OCS in the used service units.
7) The OCS sends the Reserve Units Response to acknowledge the Reserve Units Request. New service units are
granted in a Multiple Unit Operation.
8) The final answer is forwarded.
ETSI
3GPP TS 32.281 version 16.1.0 Release 16 13 ETSI TS 132 281 V16.1.0 (2020-11)
Scenario 2: Pre-quota announcement with session termination
Figure 5.2.2.2 shows the Reserve Units transactions that are required in the IMS-GWF/AS during a SIP session
establishment for which a pre-quota announcement is requested with the termination of the session.
IMS-GWF
S-CSCF OCS MRFC/MRFP
/ AS
1. INVITE 1. INVITE
Service control
2. Reserve Units Request[Initial]
Credit control
3. Reserve Units Response[Initial]
3a. Establish SIP session between calling party and MRFC/MRFP as per TS 24.628 [244] and TS 24.229 [204].
3b. Announcement playback
3c. Disconnect SIP session with the MRFC/MRFP as per TS 24.628 [244] and TS 24.229 [204].
4. BYE
4. BYE
5. 200 OK 5. 200 OK
Figure 5.2.2.2: Message sequence chart for pre-quota announcement with session termination
1) An initial SIP Invite Request is received in the S-CSCF. This request is forwarded to the IMS-GWF/AS.
2) The IMS-GWF/AS sends a Reserve Units Request[Initial] to the OCS requesting service units. The online
Credit-Control session is initiated.
3) The OCS rejects the session in the Reserve Units Response with an unsuccessful Operation Result and requests
an announcement to be played to the calling party immediately. No quota is used during the announcement
playback when the SIP session is to be terminated.
3a) The IMS-GWF/AS establishes a SIP session between the calling party and an MRFC/MRFP for the requested
announcement as per TS 24.628 [244] and TS 24.229 [204].
3b) The MRFP plays the announcement to the calling party.
3c) When the announcement is complete, the IMS-GWF/AS disconnects the SIP session with the MRFC/MRFP as
per TS 24.628 [244] and TS 24.229 [204].
4) The IMS-GWF/AS and S-CSCF releases the session with a SIP BYE that is forwarded by the S-CSCF towards
the calling party. The message sequence shown here assumes that the announcement playback established a SIP
dialog with the calling party in Step 3a. For other variations of SIP session termination for use when
announcement playback utilized signalling for early media, see Annex B of TS 32.260 [20].
5) A final response is forward by the S-CSCF to the IMS-GWF/AS.
ETSI
3GPP TS 32.281 version 16.1.0 Release 16 14 ETSI TS 132 281 V16.1.0 (2020-11)
Scenario 3: Mid-quota announcement during IMS session
Figure 5.2.2.3 shows the Reserve Units transactions that are required in the IMS-GWF/AS for a mid-quota
announcement during an established IMS session, followed by session continuation.
IMS-GWF
S-CSCF OCS MRFC/MRFP
/ AS
Ongoing SIP Session
Charging trigger
encountered
1. Reserve Units Request[Update]
Credit control
2. Reserve Units Response[Update]
2a. Establish SIP session between calling party and MRFC/MRFP as per TS 24.628 [244] and TS 24.229 [204].
2b. Announcement playback
2c. Re-connect the called party, disconnecting the MRFC/MRFP, as per TS 24.628 [244] and TS 24.229 [204].
SIP Session Continues
Figure 5.2.2.3: Message sequence chart for mid-quota announcement during IMS session
1) During an ongoing SIP session, a charging trigger encountered for an update as per table 5.3.1.1 in TS 32.260
[20]. The IMS-GWF/AS sends a Reserve Units Request[Update] to the OCS requesting service units.
2) The OCS grants units in a Multiple Unit Operation of the Reserve Units Response with a successful Operation
Result and requests an announcement to be played to the calling party prior to quota exhaustion. Announcement
information may indicate whether or not the granted quota for the IMS session shall be used for playing the
announcement. The announcement is indicated as to be played to a specified duration before the end of the quota
is reached.
2a) When the timing conditions are met for the requeted announcement, the IMS-GWF/AS establishes a SIP session
between the calling party and an MRFC/MRFP for the requested announcement as per TS 24.628 [244] and TS
24.229 [204].
2b) The MRFP plays the announcement to the calling party.
2c) When the announcement is complete, the IMS-GWF/AS re-connects the called party, disconnecting the SIP
session with the MRFC/MRFP as per TS 24.628 [244] and TS 24.229 [204].
ETSI
3GPP TS 32.281 version 16.1.0 Release 16 15 ETSI TS 132 281 V16.1.0 (2020-11)
Scenario 4: Post-quota announcement with IMS session termination
Figure 5.2.2.4 shows the Reserve Units transactions that are required in the IMS-GWF/AS for a post-quota
announcement which is initiated at final quota exhaust.
IMS-GWF
S-CSCF OCS MRFC/MRFP
/ AS
Ongoing SIP Session
Charging trigger
encountered
1. Reserve Units Request[Update]
Credit control
2. Reserve Units Response[Update]
Quota exhausted
3. BYE
3. BYE
4. 200 OK
4. 200 OK
5a. Establish SIP session between calling party and MRFC/MRFP as per TS 24.628 [244] and TS 24.229 [204].
5b. Announcement playback
5c. Disconnect the MRFC/MRFP, as per TS 24.628 [244] and TS 24.229 [204].
6. BYE
6. BYE
7. Reserve Units Request[Terminate]
Credit control
8. Reserve Units Response[Terminate]
9. 200 OK
9. 200 OK
Figure 5.2.2.4: M
...