ETSI TR 122 950 V15.0.0 (2018-07)

Digital cellular telecommunications system (Phase 2+) (GSM); Universal Mobile Telecommunications System (UMTS); LTE; Priority service feasibility study (3GPP TR 22.950 version 15.0.0 Release 15)

RTR/TSGS-0122950vf00

General Information

• Status: Published
• Publication Date: 15-Jul-2018
• Technical Committee: 3GPP SA 1 - Services
• Current Stage: 12 - Completion
• Completion Date: 16-Jul-2018

Standards Content (Sample)

TECHNICAL REPORT
Digital cellular telecommunications system (Phase 2+) (GSM);
Universal Mobile Telecommunications System (UMTS);
LTE;
Priority service feasibility study
(3GPP TR 22.950 version 15.0.0 Release 15)

3GPP TR 22.950 version 15.0.0 Release 15 1 ETSI TR 122 950 V15.0.0 (2018-07)

Reference
RTR/TSGS-0122950vf00
Keywords
GSM,LTE,UMTS
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3GPP TR 22.950 version 15.0.0 Release 15 2 ETSI TR 122 950 V15.0.0 (2018-07)
Intellectual Property Rights
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Foreword
This Technical Report (TR) 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 "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.
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Contents
Intellectual Property Rights . 2
Foreword . 2
Modal verbs terminology . 2
Foreword . 4
Introduction . 4
1 Scope . 5
2 References . 5
3 Definitions and abbreviations . 7
3.1 Definitions . 7
3.2 Abbreviations . 7
4 High Level requirements . 7
4.1 Priority Call Origination . 7
4.2 Priority Call Termination . 7
4.3 Priority Call Progression . 7
4.4 Priority Radio Resource Queuing . 7
4.5 Priority Levels . 8
4.6 Invocation on Demand . 8
4.7 Applicability to Telecommunications Services . 8
4.8 Authorization . 8
4.9 Priority Service Service Code . 8
4.10 Roaming . 9
4.11 Handover . 9
4.12 Charging Data Record . 9
4.13 Priority Trunk Queuing . 9
4.14 Coexistence with eMLPP . 9
5 Additional Description of Priority Service . 9
5. 1 At call origination . 9
5. 2 During call progression . 10
5. 3 At call termination . 10
5.4 Exception Procedures or Unsuccessful Outcome . 10
5.5 Features Interactions. 11
6 Priority Service Gap Analysis . 12
6.1 Service Accessibility . 12
6.1.1 Summary of Service Accessibility Capabilities . 12
6.1.2 Support for Priority Service . 12
6.2 Enhanced Multi-Level Precedence and Pre-emption (eMLPP) . 16
6.2.1 Summary of eMLPP Capabilities . 16
6.2.2 Support for Priority Service . 18
6.3 Subscriber Identity Module (SIM) Specifications . 22
6.3.1 Summary of SIM-based Capabilities . 22
6.3.2 Support for Priority Service . 23
6.4 Assignment request Priority Information Element . 27
6.4.1 Summary and coding of Priority Information Element Capabilities . 27
6.4.2 Support for Priority Service . 28
7 Conclusions . 32
Annex A (Informative): Regional Priority Service Requirements . 34
Annex B (Informative): Change history . 37
History . 39

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3GPP TR 22.950 version 15.0.0 Release 15 4 ETSI TR 122 950 V15.0.0 (2018-07)
Foreword
rd
This Technical Report 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.
Introduction
This Technical Report (TR) presents the results of the Feasibility Study on Priority Service. The intent of this
Feasibility Study is to assess the ability of 3GPP specifications to meet high-level requirements identified for Priority
Service. This Feasibility Study consisted of a multi-step process, namely:
1. Identify high-level requirements for Priority Service.
2. Determine existing relevant 3GPP specifications for Priority Service.
3. Perform a Gap Analysis to assess the ability of existing 3GPP specifications to meet the high-level Priority
Service requirements.
As defined in this document, Priority Service allows qualified and authorized users to obtain priority access to the next
available radio (voice or data traffic) channels on a priority basis before other PLMN users during situations when
PLMN congestion is blocking call attempts. In addition, Priority Service supports priority call progression and call
completion to support an “end-to-end” priority call.
Priority Service is intended to be used by qualified and authorized users, i.e., emergency service personnel, only during
times of emergency situations and network congestion. Access to Priority Service is limited to key personnel and those
with leadership responsibilities and is not intended for use by all emergency service personnel. This is to ensure that
non-emergency service personnel cannot “take over” the network and deny the other non-emergency service subscribers
a reasonably level of service.
Priority Service providers should adhere to uniform, nationwide operating access procedures. Priority Service can
provide significant benefits for public safety. There may be times during emergencies when non-Priority Service
subscribers will be unable to obtain access to their wireless services (because Priority Service personnel are using the
channels); nevertheless, the benefits of Priority Service outweigh any inconvenience to non-Priority Service subscribers.
Priority Service is to be available at all times in equipped markets in both the HPLMN and VPLMN within a country
where the PLMN provider is offering the service. The capability for pre-emption should be supported, with the option
to turn it on/off depending on regional requirements. Priority Service is applicable to both GERAN and UTRAN and is
activated on a per call basis using Priority Service dialing procedures.
Priority Service, supported by the 3GPP system set of services and features, is one element in ability to deliver calls of a
high priority nature from mobile to mobile networks, mobile to fixed networks, and fixed to mobile networks.
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1 Scope
This Technical Report (TR) presents the results of the Feasibility Study on Priority Service. The intent of this
Feasibility Study is to assess the ability of 3GPP specifications to meet high-level requirements identified for Priority
Service. This Feasibility Study consisted of a multi-step process, namely:
1. Identify high-level requirements for Priority Service.
2. Determine existing relevant 3GPP specifications for Priority Service.
3. Perform a Gap Analysis to assess the ability of existing 3GPP specifications to meet the high-level Priority
Service requirements.
Additional functionalities not documented in this TR are considered outside the scope of this TR. Such additional
functionality may be on a network-wide basis, nation-wide basis or particular to a group of users. Such additional
functionality shall not compromise conformance to the requirements of the Priority Service defined in this specification.
The Priority Service is intended to be utilised for both Voice and Data and therefore both elements are considered
within the scope of this document. While Priority Service is meant for both Voice and Data services, the initial set of
requirements address Circuit Switched Services (Voice as well as Data). Multimedia and non-circuit switched aspects
of Priority Service have not been addressed in this feasibility study and are for further study.
The Priority Service is intended to interwork with external networks to provide an end-to-end service. Therefore,
service interactions with external networks are considered within the scope of this document, although the specification
of these interactions may be in other standards. If this occurs, a reference to that specification shall be made.
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 41.001: "GSM Release specifications".
[2] TS 21.905: "Vocabulary for 3GPP Specifications"
[3] ETSI TS 100 921 version 7.0.1 (1999-07), Digital cellular telecommunications system (Phase 2+);
Service accessibility (GSM 02.11 version 7.0.1 Release 1998)
[4] 3GPP TS 22.011 version 3.5.0 (2005-01), 3rd Generation Partnership Project; Technical
Specification Group Services and System Aspects; Service accessibility (Release 1999)
[5] 3GPP TS 22.011 version 4.4.0 (2005-01), 3rd Generation Partnership Project; Technical
Specification Group Services and System Aspects; Service accessibility (Release 4)
[6] ETSI EN 300 924 version 7.0.1 (2005-01), Digital cellular telecommunications system (Phase 2+);
enhanced Multi-Level Precedence and Pre-emption (eMLPP) – Stage 1 (GSM 02.67 version 7.0.1
Release 1998)
[7] 3GPP TS 03.67 version 7.2.0 (2005-01), 3rd Generation Partnership Project; Technical
Specification Group Core Network; Digital cellular telecommunications system (Phase 2+);
enhanced Multi-Level Precedence and Pre-emption (eMLPP) – Stage 2 (Release 1998)
[8] ETSI EN 300 927 version 7.0.1 (2005-01), Digital cellular telecommunications system (Phase 2+);
enhanced Multi-Level Precedence and Pre-emption (eMLPP) – Stage 3 (GSM 04.67 version 7.0.1
Release 1998)
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[9] 3G TS 22.067 version 3.0.1 (1999-10), 3rd Generation Partnership Project; Technical
Specification Group Services and System Aspects; enhanced Multi-Level Precedence and Pre-
emption (eMLPP) – Stage 1 (Release 1999)
[10] 3GPP TS 23.067 version 3.3.0 (2005-01), 3rd Generation Partnership Project; Technical
Specification Group Core Network; enhanced Multi-Level Precedence and Pre-emption (eMLPP)
– Stage 2 (Release 1999)
[11] 3GPP TS 24.067 version 3.3.0 (2005-01), 3rd Generation Partnership Project; Technical
Specification Group Core Network; enhanced Multi-Level Precedence and Pre-emption (eMLPP)
– Stage 3 (Release 1999)
[12] 3G TS 22.067 version 4.0.0 (2005-01), 3rd Generation Partnership Project; Technical
Specification Group Services and System Aspects; enhanced Multi-Level Precedence and Pre-
emption (eMLPP) – Stage 1 (Release 4)
[13] 3GPP TS 23.067 version 4.1.0 (2005-01), 3rd Generation Partnership Project; Technical
Specification Group Core Network; enhanced Multi-Level Precedence and Pre-emption (eMLPP)
– Stage 2 (Release 4)
[14] 3GPP TS 24.067 version 4.1.0 (2005-01), 3rd Generation Partnership Project; Technical
Specification Group Core Network; enhanced Multi-Level Precedence and Pre-emption (eMLPP)
– Stage 3 (Release 4)
[15] GSM 11.11 v7.6.1, Specification of the Subscriber Identity Module - Mobile Equipment (SIM -
ME) interface; Release 1998
[16] GSM 04.08 v7.13.0, Mobile Radio Interface Layer 3 Specification; Release 1998
[17] 3GPP TS 11.11 v8.5.0, Specification of the Subscriber Identity Module - Mobile Equipment (SIM
- ME) interface; Release 1999
[18] 3GPP TS 51.011 v4.1.0, Specification of the Subscriber Identity Module - Mobile Equipment
(SIM - ME) interface; Release 4
[19] 3GPP TS 08.08 v. 7.7.0, Mobile-services Switching Centre- Base Station System (MSC - BSS)
interface Layer 3 specification; Release 1998
[20] 3GPP TS 08.08 v. 8.12.0, Mobile-services Switching Centre- Base Station System (MSC - BSS)
interface Layer 3 specification; Release 1999
[21] 3GPP TS 08.08 v. 9.0.0, Mobile-services Switching Centre- Base Station System (MSC - BSS)
interface Layer 3 specification; Release 4
[22] 3GPP TS 25.413 v. 3.9.0, UTRAN Iu interface RANAP signalling; Release 1999
[23] 3GPP TS 25.413 v. 4.2.0, UTRAN Iu interface RANAP signalling; Release 4
[24] 3GPP TS 24.008 v. 3.11.0, Mobile radio interface layer 3 specification; Core Network Protocols -
Stage 3; Release 1999
[25] 3GPP TS 24.008 v. 4.4.0, Mobile radio interface layer 3 specification; Core Network Protocols -
Stage 3; Release 4
[26] ITU Recommendation I.255.3, Multi-Level Precedence and Preemption Service (MLPP), 1990
[27] ITU Recommendation Q.85, Stage 2 Description for Community of Interest Supplementary
Services, Section 3 – Multi-Level Precedence and Preemption (MLPP) (rev. 1), 1992
[28] ITU Recommendation Q.735, Stage 3 Description for Community of Interest Supplementary
Services using SS No. 7, Section 3 – Multi-Level Precedence and Preemption (MLPP), 1993
[29] GSM 11.14, Specification of the SIM Application Toolkit for the Subscriber Identity Module -
Mobile Equipment (SIM - ME) interface
[30] 3GPP TS 31.102, Characteristics of the USIM Application
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[31] 3GPP TS 31.111, USIM Application Toolkit (USAT)
[32] 3GPP TS 25.321, Medium Access Control (MAC) protocol specification
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply.
Priority Service: A service that allows qualified and authorized users to obtain priority access to the next available
radio (voice or data traffic) channels during situations when PLMN congestion is blocking call attempts. In addition,
Priority Service supports priority call progression and call completion to support an “end-to-end” priority call.
Service User: A user subscribed to Priority Service.
3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply:
CDR Charging Data Record
eMLPP Enhanced Multi-Level Precedence and Pre-emption
ISDN Integrated Services Digital Network
MLPP Multi-Level Precedence and Pre-emption
PIN Personal Identification Number
PIE Priority Information Element
PSTN Public Switched Telephone Network
SC Service Code
UE User Equipment
4 High Level requirements
The following sections describe the high-level requirements to support Priority Service. These high-level requirements
are used as a basis for the gap analysis described in Section 6.
4.1 Priority Call Origination
A call shall receive priority treatment (priority access to voice or traffic channels) on the originating side, when the call
is setup by a Service User using the priority service dialling procedure described in section 4.9.
4.2 Priority Call Termination
A call shall receive priority treatment (priority access to voice or traffic channels) on the terminating side, when the call
is setup by a Service User using the priority service dialling procedure described in section 4.9.
4.3 Priority Call Progression
The Priority Service user shall receive priority call treatment/progression through the mobile network(s). A priority call
should be given higher priority over normal calls in the originating mobile network, to interconnected networks
(including the PSTN) and in the terminating network. Note: The ISDN MLPP feature may be used for signalling of
priority level in the core network.
4.4 Priority Radio Resource Queuing
Priority Service assumes a signalling channel is always available.
When a Priority Service call encounters a “no radio available” condition in the call path involving an access or egress
air-interface, or both, and,
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- at call origination, and upon recognition of the Priority Service dialing pattern, the Priority Service call is queued
in the cell serving the calling party and processed for the next available radio channel in that cell in accordance
with the caller’s priority level and call initiation time.
- at call termination upon recognition of a priority call indication in an incoming call, the Priority Service call is
queued in the cell serving the called party and processed for the next available radio channel in that cell in
accordance with the call’s priority level and arrival time.
4.5 Priority Levels
The Priority Service subscriber shall be assigned one of n priority levels. Priority levels are defined as 1, 2, 3,…,n , with
1 being the highest priority level and n being the lowest priority level. Refer to Annex A for Regional requirements for
priority levels.
4.6 Invocation on Demand
Priority Service is invoked only when requested and an idle voice or traffic channel required for an origination request
is not available.
If an idle voice or traffic channel is available when Priority Service is requested, the origination request is allowed to
proceed normally without delay.
Invocation of Priority Service at access (origination), during call progression (end-to-end), or egress (termination) is
considered complete when one of the following occurs:
- A radio (voice or traffic) channel is assigned to the call (at origination or termination),
- The loss of radio contact or roaming to another PLMN provider’s system (at origination only),
- The subscriber cancels the request by pressing the END key.
- Expiration of the maximum allowed time to hold for the next available radio (voice or traffic) channel (at
origination or termination), or
- Deletion of the Priority Service request due to arrival of a higher priority request coupled with lack of queue
capacity (at origination or termination).
4.7 Applicability to Telecommunications Services
Priority Service shall be applicable to voice and data telecommunications services that require a voice or traffic channel
assignment.
4.8 Authorization
A subscriber invoking Priority Service on call origination is authorized based on the caller’s subscription. It should also
be possible for an additional second level of authentication (e.g., by the use of PIN) to identify that the user is
authorized to make a priority call. In this case, authorization of the subscriber may be realized by the usage of a PIN.
The PIN solution is for further study and needs to be standardized. The user priority levels (1-n) and the associated PINs
are assigned by the appropriate national authority and are fixed, i.e., a subscriber may not be allowed to change the PIN
or the priority level. Note: There are some concerns related to security for “PIN Authorization”.
4.9 Priority Service Service Code
Priority Service is manually requested by adding on the Priority Service service code (SC) to the origination request, as
in:
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Figure 1: Priority Service manual request
4.10 Roaming
Priority Service shall be able to be supported during roaming when the roaming network supports Priority Service.
4.11 Handover
Priority Service shall be able to be supported during handover.
4.12 Charging Data Record
The system should record the following Priority Service charging data record (CDR) information, in addition to non-
Priority Service CDR information:
a Priority Service invocation attempts.
b Call legs (origination and/or termination) on which Priority Service was used to gain access to the radio channel.
c Recording of appropriate Priority Service information (e.g., Priority Level, PIN usage indication). Note: The
value of recording this information in CDRs is for further study.
4.13 Priority Trunk Queuing
Priority Service shall be able to support queuing of Priority Service calls for trunk resources. Trunk queuing provides
the capability to place a Priority Service call that has experienced a congestion condition for trunk resources (e.g., no
circuit available) into a queue associated with a trunk group until a trunk becomes available or until a maximum trunk
queuing time has expired. Priority Trunk Queuing applies to ISDN User Part (ISUP) and Multi-Frequency (MF) trunks.
4.14 Coexistence with eMLPP
As a service provider option, it shall be possible to offer Priority Service and eMLPP within the same network, but not
to the same user.
5 Additional Description of Priority Service
5. 1 At call origination
If a user invokes and is authorized for Priority Service and a radio (voice or traffic) channel is available, then the call is
allowed to proceed in the originating system. The call is given priority treatment during progression through the
network.
If a user invokes and is authorized for Priority Service but a radio (voice or traffic) channel is not available, the call is
queued for the next available radio channel in the cell in accordance with the user’s priority level and call initiation
time. The user should be given an indication that the call is progressing. The network treats the user as busy while a
priority call request for the user is queued.
If a user invokes and is authorized for Priority Service and a radio (voice or traffic) channel is not available, if the queue
for the cell is full, and if the user’s Priority Service priority is higher than one or more Priority Service calls already in
the queue, then the lowest, most recent call in the queue is dropped from the queue. The user’s call is placed in the
queue in accordance with the user’s priority level and call initiation time. The user should be given an indication that
the call is progressing. The network treats the user as busy while a priority call request for the user is queued.
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It is desirable that if the system changes the resources allocated to a Service User (e.g., cell handover), the call set-up
should proceed, as if the resources had remained the same (e.g., queue status). Note: The handling of queue status
during handover is for further study.
The following indications should be provided to the subscriber:
i Acceptance of a Priority Service request.
ii Rejection of a Priority Service request.
iii Loss of a pending request (including loss of radio contact and possibly roaming to another system).
A priority call request may be removed from the queue by the Service User pressing the END key. The request shall
also be removed by the system, if radio contact is not maintained with the requesting UE.
5. 2 During call progression
The Priority Service call receives priority treatment for call routing to interconnected networks supporting priority.
5. 3 At call termination
If a terminating radio (voice or traffic) channel is available, the call is terminated to the called party.
If a terminating radio (voice or traffic) channel is not available, the call is queued for the next available radio channel in
the cell serving the called party in accordance with the call’s priority level. When a terminating radio channel becomes
available and is assigned to the call, the call is terminated to the called party.
If a terminating radio (voice or traffic) channel is not available, the queue for the cell serving the called party is full, and
the call’s priority level is higher than one or more Priority Service calls in the queue, then the lowest, most recent call in
the queue is dropped from the queue. The user’s call is entered in the queue in accordance with the call’s priority level.
When a terminating radio channel becomes available and is assigned to the call, the call is terminated to the called
party.
It is desirable that if the system changes the resources allocated to the called party (e.g., cell handover), the call set-up
should proceed, as if the resources had remained the same (e.g., queue status).
5.4 Exception Procedures or Unsuccessful Outcome
At call origination, the following exceptions or unsuccessful outcomes can occur:
1 If the user invokes but is not subscribed to Priority Service, call setup is not allowed to proceed and the call is
dropped.
2 If the user invokes and is subscribed to Priority Service but the user’s mobile set times out while the call is
undergoing Priority Service call queue processing, the user’s mobile returns to the null state and the call is
dropped.
3 If a user invokes and is subscribed to Priority Service, a radio channel is not available, and the queue for the cell
is full, and the user’s Priority Service priority is lower than all of the Priority Service calls in the queue, the call
is dropped.
4 If a user invokes and is subscribed to Priority Service, and is queued for a radio channel, but the user loses
coverage, the call is removed from the queue and is dropped.
5 If a user invokes and is subscribed to Priority Service, and is queued for a radio channel, but the maximum
allowed call time in queue expires before a radio channel becomes available in the cell, the call is removed from
the queue and is dropped.
6 If a user invokes and is subscribed to Priority Service, and is queued for a trunk resource, but the user loses
coverage, the call is removed from the trunk queue and is dropped.
7 If a user invokes and is subscribed to Priority Service, and is queued for a trunk resource, but the maximum
allowed call time in queue expires before a trunk resource becomes available in the cell, the call is removed from
the trunk queue and is dropped.
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At call termination the following exceptions or unsuccessful outcomes can occur:
1 If a radio channel is not available and the queue for the cell is full, but the calling party’s priority is lower than
all of the Priority Service calls in the queue, the call is not completed and the Service User is given an
appropriate indication.
2 If the call is queued for a radio channel but the called party’s mobile loses coverage, the call is removed from the
queue and the Service User is given an appropriate indication.
3 If the call is queued for a radio channel but the maximum allowed call time in queue expires before a radio
channel becomes available in the designated terminating cell, the call is removed from the queue and the Service
User is given an appropriate indication.
5.5 Features Interactions
Call Waiting
Priority Service call users will not receive an incoming call indication while the call is being queued.

Call forwarding and call re-direction
Service users will not be allowed to invoke Priority Service calls through call forwarding or re-direction.
(E.g., "*SC + termination address" as a forwarded-to number, or Priority Service invocation through other re-direction
services, such as IN DP12 Redirection etc.)

Call Origination Restrictions
Priority Service shall override Call origination Restrictions for Barring of Outgoing Calls (BAOC), Barring of outgoing
International Calls (BOIC) and Barring of Outgoing International Calls except to Home PLMN Country (BOIC-exHC),
as a network option. Note: This may be necessary only for the PIN-based solution.

eMLPP (USA regional requirement)
Priority Service call attempt shall override any eMLPP priority levels that may be received from eMLPP capable mobile
phones. That is Priority Service users shall be able to only invoke their assigned priority level. If a Priority Service user
has an eMLPP capable phone and attempts to use an eMLPP priority level in addition to Priority Service *SC dialing,
the eMLPP priority level request will be ignored by the network.

Prepaid service
Priority Service applies only to post-paid calls. Users shall not be allowed to subscribe to Priority Service and Prepaid.

Emergency Calls (USA regional requirement)
There is no interaction between Priority Service and emergency calls. If a service user dials *SC + [emergency call
number], the call either receives radio traffic channel priority access treatment based on the service user’s priority level
or the call is denied. If a non-service user dials *SC + [emergency call number], the call is denied.
ETSI
3GPP TR 22.950 version 15.0.0 Release 15 12 ETSI TR 122 950 V15.0.0 (2018-07)
6 Priority Service Gap Analysis
6.1 Service Accessibility
Service Accessibility is specified in:
Release 1998:
- ETSI TS 100 921 version 7.0.1 (1999-07), Digital cellular telecommunications system (Phase 2+); Service
accessibility (GSM 02.11 version 7.0.1 Release 1998);
Release 1999:
rd
- 3GPP TS 22.011 version 3.5.0 (2005-01), 3 Generation Partnership Project; Technical Specification Group
Services and System Aspects; Service accessibility (Release 1999); and
Release 4:
rd
- 3GPP TS 22.011 version 4.4.0 (2005-01), 3 Generation Partnership Project; Technical Specification Group
Services and System Aspects; Service accessibility (Release 4).
Service Accessibility supports an Access Control capability that is pertinent to Priority Service.
6.1.1 Summary of Service Accessibility Capabilities
The Access Control capability prevents mobile users from initiating call origination attempts and from responding to
pages in specific areas (e.g., in emergency situations where resource shortages exist). Access control is intended to
allow network operators to prevent overload of radio access channels under critical conditions.
The basic mechanism is administered as follows: All SIMs are randomly assigned to one of ten access classes (0 – 9). In
addition, SIMs may also be members of one or more of five special categories (access classes 11 to 15). These special
classes are designated for specific purposes as summarized in the following table:
Table 1: Service Accessibility Access Classes
Access Class Usage Applicability
15 PLMN Staff Home PLMN Only
14 Emergency Services Home and Visited PLMNs
of home country only
13 Public Utilities
12 Security Services
11 For PLMN Use Home PLMN Only
0 - 9 General Use Home and Visited PLMNs

In an emergency situation, broadcast messages are used (on an individual cell basis) to indicate the “Access Classes” of
subscribers that are barred from network access. Any number of classes may be barred at any one time. For example, to
reduce approximately 20 percent of the basic mobile traffic in a given cell, broadcast messages might indicate that two
of the basic access classes should be barred from access. Upon receiving an emergency broadcast message, those
mobiles belonging to the barred access classes (and not also being members of any of the special classes) should not
initiate a call attempt or respond to a page . In addition, broadcast messages use “access class 10” to indicate whether
network access is allowed for emergency calls.
Access Control is designed to suppress not only the ability of non-priority end users to seize traffic channels, but also
the ability of those end users to use signaling channels for call attempts. Service Accessibility, as specified, cannot be
turned on and off by the end user.
6.1.2 Support for Priority Service
The following table identifies Service Accessibility support for Priority Service.

If a mobile is a member of at least one permitted Access Class, as signaled over the air interface, and the Access Class is applicable in the
serving network, access attempts are allowed. Otherwise access attempts are not allowed.
ETSI
3GPP TR 22.950 version 15.0.0 Release 15 13 ETSI TR 122 950 V15.0.0 (2018-07)
Table 2: Service Accessibility Gap Analysis
ETSI
3GPP TR 22.950 version 15.0.0 Release 15 14 ETSI TR 122 950 V15.0.0 (2018-07)
Priority Service Description Service Comments
Requirement Item Accessibility
Support
1 Priority Call A call shall receive priority treatment (priority access to voice Supported Using appropriate Access Class(es) to prevent
Origination or traffic channels) on the originating side, when the call is access attempts
setup by a Service User using the priority service dialling
procedure described in section 4.9.

2 Priority Call A call shall receive priority treatment (priority access to voice Supported Using appropriate Access Class(es) to prevent
Termination or traffic channels) on the terminating side, when the call is response to pages
setup by a Service User using the priority service dialling
procedure described in section 4.9.

3 Priority Progression The user should receive priority call treatment/progression Not supported
through the mobile network(s). A priority call should be given
higher priority over normal calls in the originating mobile
network, to interconnected networks supporting priority
(including the PSTN) and in the terminating network.
4 Priority Radio When a Priority Service call encounters a “no radio available” Not supported
Resource Queuing condition in the call path involving an access or egress air-
interface, or both, and,
at call origination, and upon recognition of the Priority Service
dialing pattern, the Priority Service call is queued in the cell
serving the calling party and processed for the next available
radio channel in that cell in accordance with the caller’s
priority level and call initiation time.
at call termination upon recognition of a priority call indication
in an incoming call, the Priority Service call is queued in the
cell serving the called party and processed for the next
available radio channel in that cell in accordance with the
call’s priority level and arrival time.
5 Priority Level The subscriber should be assigned one of n priority levels. Partially supported Ten (0-9) randomly allocated Access Classes.
Priority levels are defined as 1, 2, 3,…,n , with 1 being the Five (11-15) special classes. Enumeration of
highest priority level and n being the lowest priority level. special classes is not meant as a priority
sequence. Priority Service priority levels could
map to special Access Classes.
6 Invocation on Priority Service is invoked only when requested and an idle Not supported
Demand voice or traffic channel required for an origination request is
not available.
7 Applicability to Priority Service shall be applicable
...