ETSI ETS 300 932 ed.1 (1997-05)

Digital cellular telecommunications system (Phase 2+) (GSM); enhanced Multi-Level Precedence and Pre-emption service (eMLPP); Stage 2 (GSM 03.67 version 5.1.1)

DE/SMG-030367QR

Digitalni celični telekomunikacijski sistem (faza 2+) – Izboljšana večnivojska prednostna storitev (eMLPP) – Stopnja 2 (GSM 03.67, različica 5.1.1)

General Information

• Status: Published
• Publication Date: 02-Jun-1997
• Technical Committee: SMG 3 - Network Aspects
• Current Stage: 12 - Completion
• Due Date: 09-May-1997
• Completion Date: 03-Jun-1997
• Mandate: UIC
• Ref Project: SIST ETS 300 932 E1:2003 - Digital cellular telecommunications system (Phase 2+) (GSM); enhanced Multi-Level Precedence and Pre-emption service (eMLPP); Stage 2 (GSM 03.67 version 5.1.1)

Standards Content (Sample)

SLOVENSKI STANDARD
SIST ETS 300 932 E1:2003
01-december-2003
'LJLWDOQLFHOLþQLWHOHNRPXQLNDFLMVNLVLVWHPID]D±,]EROMãDQDYHþQLYRMVND
SUHGQRVWQDVWRULWHYH0/33±6WRSQMD*60UD]OLþLFD
Digital cellular telecommunications system (Phase 2+) (GSM); enhanced Multi-Level
Precedence and Pre-emption service (eMLPP); Stage 2 (GSM 03.67 version 5.1.1)
Ta slovenski standard je istoveten z: ETS 300 932 Edition 1
ICS:
33.070.50 Globalni sistem za mobilno Global System for Mobile
telekomunikacijo (GSM) Communication (GSM)
SIST ETS 300 932 E1:2003 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST ETS 300 932 E1:2003

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SIST ETS 300 932 E1:2003
EUROPEAN ETS 300 932
TELECOMMUNICATION May 1997
STANDARD
Source: ETSI TC-SMG Reference: DE/SMG-030367QR
ICS: 33.020
Key words: Digital cellular telecommunications system, Global System for Mobile communications (GSM)
R
GLOBAL SYSTEM FOR
MOBILE COMMUNICATIONS
Digital cellular telecommunications system (Phase 2+);
enhanced Multi-Level Precedence and Pre-emption service
(eMLPP) - Stage 2
(GSM 03.67 version 5.1.1)
ETSI
European Telecommunications Standards Institute
ETSI Secretariat
Postal address: F-06921 Sophia Antipolis CEDEX - FRANCE
Office address: 650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCE
X.400: c=fr, a=atlas, p=etsi, s=secretariat - Internet: [e-mail]
Tel.: [phone] - Fax: [phone]
Copyright Notification: No part may be reproduced except as authorized by written permission. The copyright
and the foregoing restriction extend to reproduction in all media.
© European Telecommunications Standards Institute 1997. All rights reserved.

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Whilst every care has been taken in the preparation and publication of this document, errors in content,
typographical or otherwise, may occur. If you have comments concerning its accuracy, please write to
"ETSI Editing and Committee Support Dept." at the address shown on the title page.

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Contents
Foreword .5
1 Scope.7
2 Normative references.7
3 Definitions and abbreviations .8
3.1 Definitions.8
3.2 Abbreviations .8
4 Main concepts.9
5 General architecture .11
6 Compatibility issues .12
7 Transmission.12
8 Information storage.13
8.1 Stored in the HLR.13
8.1.1 State transition model .13
8.1.2 Transfer of information from HLR to VLR.14
8.2 Stored in the VLR.14
8.3 Stored in the MSC.14
8.4 Stored in the SIM .14
8.5 Stored in the GCR.14
9 Identities.15
10 Operation and maintenance aspects .15
11 Functions and information flow.15
11.1 Subscription.15
11.2 Change of subscription.15
11.3 Call set-up .15
11.3.1 Mobile originated calls.15
11.3.1.1 Indication of priority.15
11.3.1.2 Subscription checking.15
11.3.1.3 Authentication and ciphering.16
11.3.1.4 Indication of priority to the BSC.16
11.3.1.5 Choice of radio channel .16
11.3.1.6 Indication of priority to the Mobile Station.16
11.3.2 Mobile terminated calls .16
11.3.2.1 Indication of priority.16
11.3.2.2 Indication of priority to the BSC.17
11.3.2.3 Authentication and ciphering.17
11.3.2.4 Termination with called subscriber in idle mode or group
receive mode.17
11.3.2.5 Termination with called subscriber in dedicated mode.17
11.3.3 Voice group call or voice broadcast call.17
11.3.3.1 Indication of priority to the related MSC.17
11.3.3.2 Authentication and ciphering.18
11.3.3.3 Indication of priority to the called Mobile Stations .18
11.4 Pre-emption.18

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11.4.1 Choice of communication to pre-empt.18
11.4.2 Release procedures.18
11.5 Pre-emption at handover .18
11.6 Overview of call related signalling .18
11.7 Overview of call independent signalling.26
11.7.1 Registration.26
11.7.2 Interrogation.27
Annex A (informative): Status of Technical Specification GSM 03.67.28
History.29

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Foreword
This European Telecommunication Standard (ETS) has been produced by the Special Mobile Group
(SMG) Technical Committee (TC) of the European Telecommunications Standards Institute (ETSI).
This ETS specifies the stage two description of the enhanced Multi-Level Precedence and Pre-emption
Service (eMLPP) within the digital cellular telecommunications system.
The contents of this ETS is subject to continuing work within TC-SMG and may change following formal
TC-SMG approval. Should TC-SMG modify the contents of this ETS, it will be resubmitted for OAP by
ETSI with an identifying change of release date and an increase in version number as follows:
Version 5.x.y
where:
y the third digit is incremented when editorial only changes have been incorporated in the
specification;
x the second digit is incremented for all other types of changes, i.e. technical enhancements,
corrections, updates, etc.
Transposition dates
Date of adoption: 18 April 1997
Date of latest announcement of this ETS (doa): 31 August 1997
Date of latest publication of new National Standard
or endorsement of this ETS (dop/e): 28 February 1998
Date of withdrawal of any conflicting National Standard (dow): 28 February 1998

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1 Scope
This European Telecommunication Standard (ETS) specifies the stage 2 description of the enhanced Multi-
Level Precedence and Pre-emption Service (eMLPP) which provides different call priorities in combination
with fast call set-up and pre-emption for different applications according to GSM 02.67.
2 Normative references
This ETS incorporates by dated and undated references, provisions from other publications. These
normative references are cited at the appropriate places in the text and the publications are listed
hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply
to this ETS only when incorporated in it by amendment or revision. For undated references the latest
edition of the publication referred to applies.
[1] GSM 01.04 (ETR 350): "Digital cellular telecommunications system (Phase 2+);
Abbreviations and acronyms".
[2] GSM 02.40: "Digital cellular telecommunications system; Procedures for call
progress indications".
[3] GSM 02.67 (ETS 300 924): "Digital cellular telecommunications system
(Phase 2+); enhanced Multi-Level Precedence and Pre-emption service
(eMLPP) - Stage 1".
[4] GSM 03.11 (ETS 300 928): "Digital cellular telecommunications system;
Technical realization of supplementary services".
[5] GSM 03.68 (ETS 300 933): "Digital cellular telecommunications system
(Phase 2+);Voice Group Call Service (VGCS) - Stage 2".
[6] GSM 03.69 (ETS 300 934): "Digital cellular telecommunications system
(Phase 2+);Voice Broadcast Service (VBS) - Stage 2".
[7] GSM 08.08: "Digital cellular telecommunications system (Phase 2+); Mobile
Switching Centre - Base Station System (MSC - BSS) interface; Layer 3
specification".
[8] ITU-T recommendation Q.85: "Stage 2 description for community of interest
supplementary services (clause 3: Multi-Level Precedence and Pre-emption
MLPP)".
[9] ITU-T recommendation Q.735: "Stage 3 description for community of interest
supplementary services using SS No. 7 (clause 3: Multi-Level Precedence and
Pre-emption (MLPP)".

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3 Definitions and abbreviations
3.1 Definitions
Definitions used in this ETS are also defined in GSM 02.67.
resource pre-emption: The termination of a call of a low priority user such that resources can be made
available for a precedence call of higher priority. Resource pre-emption could be initiation resource pre-
emption or handover resource pre-emption.
called-party pre-emption: Termination of a call to a particular user when a higher priority call is directed
towards that specific user. Called party pre-emption is decided by the Mobile Station. In case of point-to-
point calls, this shall be performed by Call Waiting with automatic acceptance of the waiting call by the
Mobile Station.
compatible Mobile Station: Mobile stations which support eMLPP and therefore have precedence and
pre-emption capabilities.
non-compatible Mobile Station: Mobile stations which do not support eMLPP.
3.2 Abbreviations
For the purposes of this ETS, the following abbreviations apply in addition to those listed in GSM 01.04:
eMLPP enhanced Multi-Level Precedence and Pre-emption
VBS Voice Broadcast Service
VGCS Voice Group Call Service.

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4 Main concepts
The enhanced Multi-Level Precedence and Pre-emption service (eMLPP) provides different levels of
precedence for call set-up and for call continuity in case of handover.
There are seven priority levels which are defined in GSM 02.67. The two highest levels are reserved for
network internal use. These two levels can only be used locally, i.e. in the domain of one MSC. The other
five priority levels are offered for subscription and can be applied globally, e.g. on inter switch trunks, if
supported by all related network elements, and also for interworking with ISDN networks providing the
MLPP service.
The seven priority levels are defined as follows:
A (highest, for network internal use)
B (for network internal use)
0 (for subscription)
1 (for subscription)
2 (for subscription)
3 (for subscription)
4 (lowest, for subscription)
Levels A and B shall be mapped to level 0 for priority treatment outside of the MSC area in which they are
applied.
As a network specific configuration, the ability to pre-empt other calls of lower priority and the application
of fast call set-up procedures can be assigned to each priority level. An example for an eMLPP
configuration is given in GSM 02.67.
NOTE 1: The present ETS defines the concepts for handling of priorities in the network including
the indication whether pre-emption or fast call set-up procedures are to be applied.
Note that the call set-up procedures themselves are specified in the corresponding
stage 2 descriptions of the services where they are to be used. There is presently only
a requirement for VBS and VGCS (GSM 03.69 and GSM 03.68, respectively).
NOTE 2: The network operator has to assure that the particular eMLPP configuration he applies
and the subscriptions he issues are co-ordinated with the network planning (especially
for blocking) and the implementation options applied (e.g. the use of OACSU) in order
to guarantee the service performance for the subscriber.
Considering aspects of priority handling, the following issues can be considered for each call:
a) contention during the initial random access (no specific definitions apply for eMLPP. Delays due to
access collision have to be managed by a corresponding planning of the network resources);
b) contention in gaining radio resources during the call set-up phase and during handover (this item
relates to the assignment of SDCCH and TCH for which queuing and pre-emption mechanisms are
applied for eMLPP);
A pre-emption might already be performed as a network option on the basis of the establishment
cause if a network specific eMLPP configuration assigns a certain priority level to a particular
establishment cause.
c) contention in gaining terrestrial resources inside the GSM network (this item relates to the
assignment of terrestrial channels between the GSM network nodes. Priority actions shall be
performed on basis of the MLPP service implementations. The eMLPP priority levels A and B shall
be mapped to the MLPP priority level 0. No further specific definitions apply for eMLPP);

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d) contention in gaining terrestrial resources in external networks (this item relates to interworking with
external networks which shall be performed on basis of the MLPP service if provided in the related
external networks);
e) application of different call set-up procedures in relation to the priority levels and the network
specific configuration (three classes of set-up performance are defined in GSM 02.67, one very fast
class for VBS or VGCS emergency call services, one class for fast but normal set-up times and one
class allowing some delay in the set-up. The application of the corresponding procedures shall be
decided by the network on the basis of the requested priority level);
f) automatic answering of calls if the incoming call is of or exceeds a defined priority level,
respectively, or called party pre-emption (if the called GSM subscriber is engaged in communication
of a lower priority);
g) the means by which the called user is informed of priority issues and is able to make appropriate
decisions if no called party pre-emption applies;
h) the accommodation of non-compatible Mobile Stations.
The definitions in the present ETS focus on the issues under item b), e), f), g) and h). Items c) and d) are
related to the MLPP service implementation for the signalling system No. 7 according to ITU-T
Recommendations Q.85 and Q.735.
For a call establishment, a subscriber shall be able to select any one of the priority levels he has
subscribed to.
Priorities shall be treated in the network as defined in GSM 02.67. Priority treatment is different for
point-to-point calls and voice broadcast calls or voice group calls, respectively:
- mobile originated point-to-point call:
The priority level depends on the calling subscriber. If the user has no eMLPP subscription, the call
shall have a default priority level defined in the network. If the user has an eMLPP subscription, the
call shall have the priority level selected by the user at set-up or the priority level predefined by the
subscriber as default priority level by registration.
- mobile terminated point-to-point calls:
The priority level depends on the calling party. For this, interworking with the ISDN MLPP service is
required. If the call is not an MLPP call, i.e. no priority level is defined, the call shall be treated in the
mobile network with a default priority level. If the call is an MLPP call, the call shall be treated with
the priority level provided by the interfacing network.
- mobile to mobile point-to-point calls:
The priority shall be treated for the calling subscriber as for mobile originated calls and for the called
subscriber as for mobile terminated calls. However, an interworking with MLPP is not required if
both the calling subscriber and the called subscriber are located in the same MSC area.
- Voice Broadcast Calls (VBS) and Voice Group Calls (VGCS):
The link on the voice broadcast call channel or voice group call channel shall have the priority level
as defined in the corresponding registration for the related voice broadcast call or voice group call in
the GCR. At the early stage of a voice broadcast call or voice group call establishment, before the
GCR request is made and the voice broadcast call channel or voice group call channels are
assigned, the procedure shall be the same as for point-to-point calls.
Queuing and resource pre-emption shall then be applied as appropriate according to the network service
configuration. In addition, automatic answering or called party pre-emption shall be applied as appropriated
according to the Mobile Station's internal service configuration.
The MSC shall maintain a record of the priority level of each call in progress in its area such that it can
arbitrate over resources in a defined manner.

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The priority level can be included in the CM_SERVICE_REQUEST message in the case that a user
establishing a point-to-point call is using a compatible Mobile Station (see clause 6).
If the subscriber has not selected a priority level for that call or uses a non compatible Mobile Station (see
clause 6), the priority level shall be assigned according to the respective VLR data.
The priority level of a call shall be determined by the MSC. Accordingly, the MSC shall request channel
assignment with an indication of the priority level and the pre-emption capability of that call. For this the
MSC shall use the priority message element as defined in GSM 08.08. Mapping of the priority information
in this message element on the network specific eMLPP configuration shall be performed in the MSC.
Queuing and resource pre-emption shall be performed accordingly if necessary.
In addition to the priority signalling, the requirement for a direct assignment of a TCH shall be included in
the establishment cause of the CHAN_REQ message in order to support a fast call set-up procedure in the
BSC at the earliest possible stage of the call establishment for high priority calls if applicable.
Automatic answering or, if necessary, called-party pre-emption has to be performed by the Mobile Station
as defined in the following:
- point-to-point calls:
If the user is in idle mode, the Mobile Station shall automatically connect to an incoming call of a
sufficient priority level. The priority level shall be included in the paging message and in the set-up
message. If the user is in dedicated mode and has a subscription to Call Waiting, a Call Waiting
indication including the priority level of the call shall be given to the Mobile Station which
automatically accepts the waiting call.
There is no called party pre-emption for point-to-point calls without Call Waiting.
- voice group calls and voice broadcast calls:
Notifications for other voice group calls, voice broadcast calls or information on paging for point-to-
point calls shall be given to the Mobile Stations involved in on-going voice group calls or voice
broadcast calls as defined in GSM 03.68 and GSM 03.69, respectively. The notifications include the
related priority level of the call. In case of a notified call with higher priority where called-party pre-
emption applies, the Mobile Station shall automatically leave the on-going voice group call or voice
broadcast call and react according to the type of the notified call type.
For both cases, the priority level applied shall be included, either in the paging message or Call Waiting
indication, or in the notification message, in order to enable the Mobile Station to decide on an automatic
reaction (automatic answering or called-party pre-emption) or to indicate the incoming, non pre-empting
call to the user.
The priority information of the assignment request shall also be applied for BSS internal handover. For
external handover, the MSC shall include the priority information in the handover request according to the
definition in GSM 08.08 in the same way as for the assignment request.
5 General architecture
No specific requirements are identified.

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6 Compatibility issues
eMLPP cannot be applied with standard Phase 1 or Phase 2 Mobile Stations (non compatible Mobile
Stations) with all service aspects. A dedicated Mobile Station (compatible Mobile Station) with eMLPP
capability is required.
Specific functions a compatible Mobile Station shall provide are:
- priority selection via MMI for call establishment in case of an eMLPP subscription including priority
levels above level 4;
- analysis of the priority level included in a paging message, Call Waiting indication or notification into
a voice group call or voice broadcast call, respectively;
- automatic reaction on basis of the analysed priority level in case of an incoming call while in
dedicated mode, group transmit mode or group receive mode, respectively, according to the user
defined Mobile Station configuration (for each subscribed priority level the user shall be able to
configure the Mobile Station for automatic acceptation or indication or rejection of an incoming call).
NOTE: Functions related to notifications are only required for Mobile Stations providing VBS or
VGCS functions as defined in GSM 03.69 and GSM 03.68, respectively.
However, if eMLPP is provided in a network, it can be applied to non compatible Mobile Stations in the
following way:
- calls of subscribers which have no specific eMLPP subscription shall be treated for resource pre-
emption with a default priority level.
This shall also apply independent of the use of compatible or non compatible Mobile Stations;
- calls of eMLPP subscribers which use a non compatible Mobile Station shall be treated for resource
pre-emption with the subscriber's default priority level;
- calls to eMLPP subscribers which use a non compatible Mobile Station shall be indicated to the user
by Call Waiting as normal.
7 Transmission
No specific requirements are identified.

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8 Information storage
8.1 Stored in the HLR
Information concerning the maximum priority level which a subscriber is entitled to use at call establishment
shall be stored in the HLR.
If the maximum priority level is above level 4, one level shall be indicated as default level. This default level
shall be used for mobile originated calls if no priority selection is performed by the user at call
establishment.
The default selection can be performed by the subscriber by means of a registration procedure.
NOTE: The priority levels in the subscription are related to point-to-point calls. VBS and VGCS
calls are treated with the priority level defined in the GCR for a certain group ID in a
certain group call area which can be different to the priority levels explicitly defined in
the eMLPP subscription. However, these levels are then implicitly defined with the
subscribed group IDs.
eMLPP may have the following logical states (refer to GSM 03.11 for an explanation of the notation):
Provisioning State Registration State Activation State HLR Induction State
(Not Provisioned, Not Registered, Not Active Not Induced)
(Provisioned, Registered, Active and Operative Not Induced)
The HLR shall store the logical state of eMLPP (which shall be one of the valid states listed above) on a
per subscriber basis.
8.1.1 State transition model
The following figure shows the successful cases of transition between the applicable logical states of
eMLPP. The state changes are caused by actions of the service provider.
Note that error cases are not shown in the diagram as they normally do not cause a state change.
Additionally, some successful requests may not cause a state change. Hence they are not shown in the
diagram.
Provision
(Not Provisioned, (Provisioned,
Not Registered, Registered,
Not Active, Active and Operative,
Not Induced) Not Induced)
Withdrawal
Figure 1: State transition model for eMLPP

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8.1.2 Transfer of information from HLR to VLR
If the provisioning state for eMLPP is "Provisioned" then, when the subscriber registers on a VLR, the HLR
shall send that VLR information about the logical state of eMLPP, the maximum priority level and the
default priority level.
If any of the eMLPP subscriber data is changed, the HLR shall send to the VLR the complete eMLPP
subscriber data.
8.2 Stored in the VLR
For eMLPP, the VLR shall store the service state information, the maximum priority level a subscriber is
entitled to use and the default priority level received from the HLR.
8.3 Stored in the MSC
The network specific service configuration of eMLPP defined by the network operator as specified in
GSM 02.67 shall be stored within each MSC. This includes information on resource pre-emption actions for
any given levels of incoming and on-going call priority. An example for a network specific service
configuration is given in GSM 02.67.
8.4 Stored in the SIM
Each compatible Mobile Station shall be aware of the automatic answering actions for any given levels of
priority so that when in idle mode or dedicated mode or group receive mode or group transmit mode, it can
decide on the necessary reactions to be taken according to the priority information of the incoming call.
For this, the SIM shall store the following data:
Priority level Subscription Automatic Fast set-up
available answering actions (note)
applies
A yes/no yes/no yes/no
B yes/no yes/no yes/no
0 yes/no yes/no yes/no
1 yes/no yes/no yes/no
2 yes/no yes/no yes/no
3 yes/no yes/no yes/no
4 yes/no -- yes/no
NOTE: Fast set-up actions which shall be performed by the Mobile Stations if indicated in the
SIM data are the use of the appropriate establishment cause and the reaction on
accelerated establishment procedures allowed by the network (see subclause 11.6).
The automatic reaction of the Mobile Station for automatic answering or called party pre-emption sha
...