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TECHNICAL SPECIFICATION
Digital cellular telecommunications system (Phase 2+) (GSM);
GSM Cordless Telephony System (CTS), Phase 1;
Service description;
Stage 1
(3GPP TS 42.056 version 15.0.0 Release 15)
R
GLOBAL SYSTEM FOR
MOBILE COMMUNICATIONS
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3GPP TS 42.056 version 15.0.0 Release 15 1 ETSI TS 142 056 V15.0.0 (2018-07)
Reference
RTS/TSGS-0142056vf00
Keywords
GSM
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3GPP TS 42.056 version 15.0.0 Release 15 2 ETSI TS 142 056 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
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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
.
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
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3GPP TS 42.056 version 15.0.0 Release 15 3 ETSI TS 142 056 V15.0.0 (2018-07)
Contents
Intellectual Property Rights . 2
Foreword . 2
Modal verbs terminology . 2
Foreword . 5
Introduction . 6
1 Scope . 7
2 References . 7
3 Definitions and abbreviations . 8
3.1 Definitions . 8
3.2 Abbreviations . 8
4 Description . 9
4.1 System overview . 9
4.2 Service aspects . 10
4.2.1 General . 10
4.2.2 User aspects . 10
4.2.3 Subscriptions. 11
4.2.3.1 CTS-roaming aspects . 11
4.2.3.2 Withdrawal of CTS subscription . 11
4.2.4 GSM coverage . 11
4.2.5 Mobility . 12
4.2.5.1 Mode selection between CTS and PLMN . 12
4.2.5.2 Attachment of the same CTS-MS with multiple CTS-FPs. 12
4.2.5.3 Attachment of multiple CTS-MSs with the same CTS-FP. 12
4.2.5.4 Attachment status of a CTS-MS . 13
4.2.6 CTS applications . 13
4.2.6.1 Tele-services . 13
4.2.6.2 Supplementary services . 13
4.2.6.3 Additional support for fixed network supplementary services . 13
4.2.6.4 Man Machine Interface (MMI) . 13
4.2.6.5 CTS internal calls . 14
4.2.6.6 CTS internal call transfer . 14
4.2.6.7 CTS internal call hold . 14
4.2.6.8 Mobile hunting . 14
4.2.6.9 SMS-MT . 14
4.2.6.10 SMS-MO . 14
4.2.6.11 Other services . 14
4.3 Radio interface and GSM co-existence aspects . 14
4.3.1 General principles . 14
4.3.2 Broadcast channel functionality . 15
4.4 Security requirements . 15
4.4.1 General . 15
4.4.2 Enrolment . 15
4.4.3 Attachment . 15
4.4.4 Protection of communications . 15
4.4.5 Security Parameter Storage Requirements . 15
4.4.6 De-activation. 16
5 Normal Procedures . 16
5.1 Enrolment of CTS-FP . 16
5.1.1 CTS operator procedure for enrolment of CTS-FP . 16
5.1.2 User procedure for enrolment of CTS-FP . 16
5.2 Enrolment of CTS-MSs . 17
5.3 De-enrolment of a CTS-MS . 17
5.4 Attachment of CTS-MS . 18
ETSI
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3GPP TS 42.056 version 15.0.0 Release 15 4 ETSI TS 142 056 V15.0.0 (2018-07)
5.5 Call procedures . 18
5.5.1 CTS-MS originated calls . 18
5.5.1.1 Number compatibility between GSM formats and fixed network formats . 18
5.5.2 CTS-MS terminated calls . 18
5.5.3 CTS internal calls (optional) . 19
5.5.4 CTS internal call transfer (optional) . 19
5.6 Maintenance . 19
6 CTS de-activation . 20
6.1 CTS-FP de-activation by the CTS operator . 20
6.2 CTS-FP de-activation by the user . 20
6.3 CTS-FP de-activation by self controlling features . 20
6.4 CTS-MS de-activation by the CTS operator . 20
7 Exceptional procedures . 20
8 Charging aspects . 20
9 Cross Phase Compatibility . 20
Annex A (informative): Later phases of CTS . 21
Annex B (informative): Change History . 22
History . 24
ETSI
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3GPP TS 42.056 version 15.0.0 Release 15 5 ETSI TS 142 056 V15.0.0 (2018-07)
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
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3GPP TS 42.056 version 15.0.0 Release 15 6 ETSI TS 142 056 V15.0.0 (2018-07)
Introduction
Today, there exists a clear distinction between the public mobile telephone systems for wide area coverage on the one
hand, and private cordless telephone systems for local area coverage on the other hand. Recently, attempts have been
made to integrate the wide area cellular and the local area cordless function into one and the same Mobile Equipment
(ME). However, because of the incompatibility between the existing cellular and cordless standards, this results in ME
implementations with rather low cost-efficiency.
The intention of the GSM Cordless Telephony System (CTS) is therefore to provide cordless functionality to a standard
GSM Mobile Station (MS) with minimum impact on the MS. The impact would ideally be limited to an upgrade of the
ME and SIM software. This can only be accomplished if the radio interface of the cordless system is identical, or very
similar, to the standard GSM radio interface.
ETSI
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3GPP TS 42.056 version 15.0.0 Release 15 7 ETSI TS 142 056 V15.0.0 (2018-07)
1 Scope
The scope of the present document is to describe the Service aspects of a GSM Cordless Telephony System (CTS),
which provides the possibility for users of GSM terminals to have cordless access to a fixed network, such as
PSTN/ISDN or a radio network such as GSM.
Due to the time constraints to have a first specification ready for market needs, a phased approach is necessary. The first
phase aims primarily at an application supporting the speech teleservice (including DTMF support) in a residential
single cell environment. The focus is on the requirements necessary to elaborate the radio interface and the security
aspects for such an application.
To not prevent or impede the evolution of CTS to additional services and functions, later phases may have to be
considered when now defining the means to fulfil the above mentioned requirements for the first phase of CTS.
Therefore, additional support on the CTS radio interface for later phase services (e.g. SMS, subscriber authentication
and GSM supplementary services), is included already in CTS Phase 1, provided that such services are clearly defined.
Other expected services and functions in later phases are included in annex A.
The standardisation of the physical layers of the GSM-CTS fixed network interface is not in the scope of the present
document. However, consideration may need to be given to communication of application data between CTS and
PLMN via the fixed network.
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: "Vocabulary for 3GPP Specifications".
[2] 3GPP TS 22.101: "UMTS Service Principles".
[3] 3GPP TS 42.009: "Security aspects".
[4] 3GPP TS 22.081: "Line identification Supplementary Services - Stage 1".
[5] 3GPP TS 22.096: "Name identification Supplementary Services - Stage 1".
[6] 3GPP TS 23.040: "Short Message Service (SMS)".
[7] ETSI ETS 300 111 (1992): "Integrated Services Digital Network (ISDN); Telephony 3,1 kHz
teleservice, service description".
[8] ETSI ETS 300 109 (1992): "Integrated Services Digital Network (ISDN); Circuit-mode 64 kbit/s 8
kHz structured bearer service category usable for speech information transfer, service description".
[9] ETSI ETS 300 110 (1992): "Integrated Services Digital Network (ISDN); Circuit-mode 64 kbit/s 8
kHz structured bearer service category usable for 3,1 kHz audio information transfer, service
description".
[10] ETSI EN 301 144-1 (V1.1): "The Signalling application for the mobility management service on
the alpha interface; Part 1: Protocol specification".
[11] 3GPP TS 22.030: "Man Machine Interface (MMI) of the Mobile Station (MS)".
ETSI
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3GPP TS 42.056 version 15.0.0 Release 15 8 ETSI TS 142 056 V15.0.0 (2018-07)
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply:
FP Enrolment: procedure where a CTS-FP is loaded with data necessary to obtain CTS operation. After this procedure
CTS operation may commence.
MS Enrolment: procedure where a CTS-MS is associated for the first time with a CTS-FP. After this procedure CTS-
MS has access to this CTS-FP.
Attachment: procedure where an MS attaches to a certain CTS-FP. When attached, it is possible to make and receive
calls via the CTS-FP. The CTS-MS must have been initialised correctly to the CTS-FP before attachment can take part.
Generic Frequency List (GFL): Generic Frequency List (GFL) contains all absolute radio frequency channel numbers
(ARFCN), as defined in GSM 05.05, on which the CTS-FP is allowed to operate. The CTS-FP will never use
frequencies which are not listed in the GFL.
CTS Mobile Station: GSM MS with CTS capability.
CTS Fixed Part: CTS-FP is a device which offers a personnal cordless coverage and acts as a link between the CTS-
MS and the fixed network or the GSM network.
GSM Operator: GSM operator is the operator who provides GSM cellular service to the MS.
CTS licence exempt frequencies: frequency band that may be allocated by national regulator to CTS usage outside of
a GSM licence allocated to a GSM operator.
CTS operator: CTS operator is the operator who provides the GFL to the CTS-FP. The CTS operator may be the same
than the GSM operator.
FP-SIM: FP-SIM is the SIM card inserted in the CTS-FP, which materialised the CTS subscription. The FP- SIM
belongs to the CTS operator.
CTS subscription: when a GSM licensed band is used, the right to use a CTS operator's frequency spectrum for
communication between a CTS-FP and CTS-MS(s).
CTS-FP owner: person who has the CTS-FP control and may authorise MS Enrolment.
CTS user: person who has a CTS-MS which is allowed to do CTS operations.
CTS-MS local number: number in the range of 0-99 optionally assigned to the CTS-MS at enrolment. This number is
used for CTS internal calls.
CTS-Roaming: right for an additional CTS-MS to be enrolled to a CTS-FP which is initialised to an operator other
than the HPLMN operator of the additional CTS-MS.
3.2 Abbreviations
In addition to those below, abbreviations used in the present document are listed in GSM 01.04.
CTS Cordless Telephony System
CTS-FP Cordless Telephony System - Fixed Part
CTS-MS Cordless Telephony System - Mobile Station
FP – SIM Fixed Part – Subscriber Identity Module
GFL Generic Frequency List
IFPEI International Fixed Part Equipment Identity
ISDN Integrated Services Digital Network
MS Mobile Station
PSTN Public Switched Telephone Network
SMS - MO Short Message Service - Mobile Originated
SMS - MT Short Message Service - Mobile Terminated
ETSI
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3GPP TS 42.056 version 15.0.0 Release 15 9 ETSI TS 142 056 V15.0.0 (2018-07)
4 Description
4.1 System overview
The GSM Cordless Telephone System (GSM-CTS) described in the present document is a radio communications
system based on a GSM-compatible cellular interface between a private radio base station called CTS Fixed Part (CTS-
FP) and a CTS mobile station (CTS-MS). The CTS-FP is connected either via a wireline to the PSTN/ISDN network or
via a radio connection to a GSM network.
When connected to the fixed network, the CTS-FP will be compliant with the existing fixed network standards
(e.g. support the telephony 3,1 kHz teleservice (see [7]), the speech bearer service (see [8]) and the 3,1 kHz audio bearer
service (see [9] in case of an ISDN CTS-FP and the relevant national standards in case of PSTN CTS-FP). There is no
direct radio communication between different CTS-FPs. However, this does not preclude indirect communication,
e.g. via the fixed network or via the MS.
When connected to a GSM network, the CTS-FP is compliant with the existing ETSI standards applicable to a GSM
mobile. From the GSM network point of view, the CTS-FP is seen as a standard GSM mobile including a standard
GSM SIM card. (i.e. the CTS-FP may include 2 SIM cards: one for the GSM subscription and one for the CTS
subscription).
An illustration of the CTS concept is shown in figure 1. Due to the low transmit power of the CTS-FP, the coverage
area is restricted and limited. When the CTS-MS comes in range of the CTS-FP, it may attach to the CTS. When
connected to the fixed network, from then on, the user can make and accept calls directly via the PSTN without the
intervention of the public cellular network. When attached, the MS checks whether it is still in range of the CTS and
whether it is paged. As an option, the MS may simultaneously work in both the cellular and the cordless mode, in a so
called parallel mode, i.e. be attached both in the GSM PLMN and the CTS. When the MS comes out of range of the
CTS it may switch to the GSM mode. This switch shall be indicated to the user. When the CTS-MS is in either CTS
mode or GSM mode and is searching for a potential channel to attach with in the other mode, it shall be able to respond
to paging messages from the mode in which it is currently attached.
The radio interface between the CTS-FP and the CTS-MS is a modified GSM interface. The carrier frequencies used are
the same as assigned for cellular service. These carrier frequencies can be part of a licence exempt band or a licensed
band.
When CTS-FP operates in a licenced band:
- these frequencies can be reserved by the operator for GSM-CTS usage, or can be shared with the cellular system.
In every case, however, the GSM operator controls, on an area and time basis, on which frequencies the CTS is
allowed to operate. In case of co-existence in the same operating area, a procedure shall be deployed to minimise
interference between GSM PLMN and CTS users.
NOTE: The frequencies used for CTS could be in any frequency band defined for GSM, i.e. GSM900, DCS1800
or PCS1900. This applies both to the CTS-FP and the CTS-MS.
The quality of service (e.g. service accessibility, call set-up time, bit rate for data services) of the 'GSM only'
subscribers shall remain unaffected by the introduction of CTS. Means to guarantee that the quality of service of GSM
subscribers does not degrade due to CTS introduction have to be defined.
Since the MS uses the same frequency spectrum both for the cellular mode and the cordless mode, the ME hardware can
be reused. The intention is that hardware modifications in the radio transceiver of a standard GSM ME should not be
necessary. It is also a requirement that the introduction of CTS shall not destabilise any existing GSM mobile
equipment or degrade the mobile equipment's dedicated (e.g. in call) or idle mode performance.
When a licensed band is used:
- the CTS operator can administer all CTS-FPs and the corresponding CTS. When the CTS is initialised, the
required operation parameters are downloaded into the CTS. This can either be done via the fixed network or via
the GSM radio interface.
ETSI
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3GPP TS 42.056 version 15.0.0 Release 15 10 ETSI TS 142 056 V15.0.0 (2018-07)
GSM PLMN
GSM CTS
GSM BTS
CTS Fixed
Part
Figure 1: Concept for the GSM CTS functionality when connected to the PSTN
4.2 Service aspects
4.2.1 General
In the first phase of CTS an application for residential environment serving one cell is intended. The services and
features to be supported relate to this assumption.
4.2.2 User aspects
The user of the CTS shall be required to perform a simple installation process in order to initialise the CTS operation.
This process shall include:
• connection of the CTS-FP to the power supply and to either the fixed network or the GSM network interface;
• enrolment of the CTS-FP (CTS-FP enrolment).
As the CTS-FP shall not be GSM operator specific, it has to be enrolled with operation specific data, e.g. a list of
allowed frequencies (Gene
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