ETSI TS 127 005 V16.0.0 (2020-08)

Digital cellular telecommunications system (Phase 2+) (GSM); Universal Mobile Telecommunications System (UMTS); LTE; Use of Data Terminal Equipment - Data Circuit terminating Equipment (DTE - DCE) interface for Short Message Service (SMS) and Cell Broadcast Service (CBS) (3GPP TS 27.005 version 16.0.0 Release 16)

RTS/TSGC-0127005vg00

General Information

• Status: Not Published
• Technical Committee: 3GPP CT 1 - MM/CC/SM [lu] (formely CN1)
• Current Stage: 12 - Completion
• Completion Date: 06-Aug-2020

Standards Content (Sample)

TECHNICAL SPECIFICATION
Digital cellular telecommunications system (Phase 2+) (GSM);
Universal Mobile Telecommunications System (UMTS);
LTE;
Use of Data Terminal Equipment
- Data Circuit terminating Equipment (DTE - DCE)
interface for Short Message Service (SMS)
and Cell Broadcast Service (CBS)
(3GPP TS 27.005 version 16.0.0 Release 16)

3GPP TS 27.005 version 16.0.0 Release 16 1 ETSI TS 127 005 V16.0.0 (2020-08)

Reference
RTS/TSGC-0127005vg00
Keywords
GSM,LTE,UMTS
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ETSI
3GPP TS 27.005 version 16.0.0 Release 16 2 ETSI TS 127 005 V16.0.0 (2020-08)
Intellectual Property Rights
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Modal verbs terminology
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Contents
Intellectual Property Rights . 2
Legal Notice . 2
Modal verbs terminology . 2
Foreword . 6
0 Scope . 7
0.1 References . 8
0.2 Abbreviations . 8
1 Reference configuration . 9
1.1 V.24 Interface Circuits . 9
1.1.1 Circuit definitions for the SMS Block mode . 9
1.1.2 Circuit definitions for the SMS Text and PDU modes . 10
2 SMS Block Mode . 10
2.1 Beginning and ending of SMS/CBS Block Mode . 10
2.1.1 Beginning SMS/CBS Block Mode . 10
2.1.2 Returning from SMS/CBS Block Mode To Default Mode . 11
2.2 Protocol description . 11
2.3 Requesting messages already held in the Mobile Termination . 12
2.3.1 Requesting List Of Messages. 13
2.3.2 Requesting Transfer Of Messages . 13
2.3.2.1 Requesting Transfer Of A Specific Message . 13
2.3.2.2 Requesting Transfer Of All Messages. 13
2.3.3 Requesting Diversion Of Incoming Messages . 14
2.3.3.1 Requesting SMS Messages . 14
2.3.3.2 Requesting CBS Messages . 14
2.3.3.3 Requesting indication of message arrival . 14
2.3.4 Requesting Transfer Into Mobile Termination . 15
2.3.5 Requesting Deletion Of Messages . 15
2.4 Message functional definitions and contents . 16
2.4.1 Commands Issued By The Terminal Equipment . 16
2.4.1.1 List Request. 17
2.4.1.2 Get Message . 17
2.4.1.3 Get First Message . 17
2.4.1.4 Get Next Message . 17
2.4.1.5 Transfer Inc SMS . 17
2.4.1.6 Indicate Inc SMS . 17
2.4.1.7 Transfer Inc CBS . 18
2.4.1.8 Insert SMS. 18
2.4.1.9 Delete message . 18
2.4.1.10 Unable to process . 18
2.4.1.11 End SMS Mode . 18
2.4.1.12 Acknowledge Message . 19
2.4.2 Responses/Indications Issued By The MT . 19
2.4.2.1 Message List . 19
2.4.2.2 Message . 19
2.4.2.3 Get Message Failure . 20
2.4.2.4 Inc Message. 20
2.4.2.5 Message Arrived . 20
2.4.2.6 Insert SMS Complete . 20
2.4.2.7 Insert SMS Failure . 20
2.4.2.8 Delete Message Complete . 21
2.4.2.9 Delete Message Failure . 21
2.4.2.10 Unable To Process . 21
2.4.2.11 End SMS Mode . 21
2.4.2.12 Request Confirmed. 21
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2.5 General message format and information elements coding . 21
2.5.1 Message Type . 21
2.5.2 Other Information Elements . 22
2.5.2.1 Short Message Reference . 22
2.5.2.2 SMS Transfer Type . 23
2.5.2.3 Indication Type . 23
2.5.2.4 Insert Type . 24
2.5.2.5 Short Message Index . 25
2.5.2.6 Short Message Data. 26
2.5.2.7 Cause . 28
2.5.2.8 Index Count . 29
2.5.2.9 CBS Transfer Type . 29
2.5.2.10 Page Index . 29
2.5.2.11 Last Short Message . 30
2.5.2.12 Confirm Type . 30
2.5.2.13 TP-Failure Cause . 31
2.5.2.14 SM-Deliver-Ack . 31
2.5.2.15 SM-Submit-Ack . 32
3 Text Mode . 32
3.1 Parameter Definitions . 32
3.2 General Configuration Commands . 35
3.2.1 Select Message Service +CSMS . 35
3.2.2 Preferred Message Storage +CPMS . 36
3.2.3 Message Format +CMGF . 36
3.2.4 Enter SMS Block Mode Protocol +CESP . 37
3.2.5 Message Service Failure Result Code +CMS ERROR . 37
3.2.6 Informative Examples . 38
3.3 Message Configuration Commands . 38
3.3.1 Service Centre Address +CSCA . 38
3.3.2 Set Text Mode Parameters +CSMP . 38
3.3.3 Show Text Mode Parameters +CSDH . 39
3.3.4 Select Cell Broadcast Message Types +CSCB . 39
3.3.5 Save Settings +CSAS . 40
3.3.6 Restore Settings +CRES . 40
3.3.7 Informative Examples . 41
3.4 Message Receiving and Reading Commands . 41
3.4.1 New Message Indications to TE +CNMI . 41
3.4.2 List Messages +CMGL . 46
3.4.3 Read Message +CMGR . 47
3.4.4 New Message Acknowledgement to ME/TA +CNMA . 47
3.4.5 Informative Examples . 48
3.5 Message Sending and Writing Commands . 49
3.5.1 Send Message +CMGS . 49
3.5.2 Send Message from Storage +CMSS . 50
3.5.3 Write Message to Memory +CMGW . 50
3.5.4 Delete Message +CMGD . 51
3.5.5 Send Command +CMGC . 52
3.5.6 More Messages to Send +CMMS . 52
3.5.7 Informative Examples . 53
4 PDU Mode . 53
4.0 General . 53
4.1 List Messages +CMGL . 54
4.2 Read Message +CMGR . 54
4.3 Send Message +CMGS . 54
4.4 Write Message to Memory +CMGW . 55
4.5 Send Command +CMGC . 56
4.6 New Message Acknowledgement to ME/TA +CNMA . 56
4.7 Send Message from Storage +CMSS . 57
Annex A (normative): Character Set Conversions for SMS Text Mode . 58
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Annex B (informative): Example of processing a data block . 61
B.1 Example state diagrams for the block receiver. 61
B.2 Example of coding and decoding a data block . 61
Annex C (informative): Change History . 68
History . 69

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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 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 specification;
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0 Scope
The present document defines three interface protocols for control of SMS functions within a GSM/UMTS mobile
telephone from a remote terminal via an asynchronous interface.
Clause 2 defines a binary protocol ("Block Mode"). The protocol includes error protection and is suitable for use where
the link may not be completely reliable. It will be of particular use where control of remote devices is required. Efficient
transfer of binary encoded user data is possible.
Clause 3 defines a character-based interfaced based on "AT" commands ("Text Mode"). This mode is suitable for
unintelligent terminals or terminal emulators, and for application software built on command structures like those
defined in V.25ter. Some of the commands defined in clause 3 will also be useful for implementations of clause 2
and/or clause 4, for example enabling an indication of incoming SMS messages.
Clause 4 defines a character-based interface with hex-encoded binary transfer of message blocks ("PDU Mode"). This
mode is suitable for software drivers based on AT command structures which do not understand the content of the
message blocks and can only pass them between the MT and "upper level" software resident in the TE.
In all three modes, the terminal is considered to be in control for SMS/CBS transactions.
The present document considers the mobile termination to be a single entity. Other 3GPP/GSM Technical
Specifications describe the split of functionality between the mobile equipment and (U)SIM.
The three "modes" referred to above, are represented in figure 0.1.
The "Block mode" is a self contained mode in its own right, and when entered, control will remain within that mode
until the procedures to exit the mode are executed, after which control is returned to the V.25ter "command" state or
"on-line command" state.
The "Text" and "PDU" modes are not in themselves V.25ter states but are simply sets of commands which will operate
in either the V.25ter "command" state or "on-line command" state. The "Text" and "PDU" modes are transitory states
and after each operation, control is automatically returned to the V.25ter "command" state or "on-line command" state.
Whilst in the V.25ter command state, the MS is available to handle incoming and outgoing calls such as Data or
Facsimile.
V.25ter
"command" state
and "on-line command" state
SMS SMS
Text PDU
Mode Mode
SMS Block Mode
Figure 0.1: Block, Text and PDU modes
In the "Block mode" and "PDU" mode a mobile is not permitted to modify any component of an SMS/CBS message
received from the air interface or an SMS message received from a TE, before passing it on, except where
3GPP TS 23.040 [3] or 3GPP TS 23.041 [4] defines a "component modification facility" and where this "component
modification facility" is supported by the mobile. In the Text Mode the mobile may be unable to display characters
coded in particular coding schemes. In this case, the mobile shall behave as described in 3GPP TS 23.038 [2] and
assume the coding scheme to be the GSM 7 bit default alphabet.
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0.1 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] Void.
[2] 3GPP TS 23.038: "Alphabets and language-specific information".
[3] 3GPP TS 23.040: "Technical realization of the Short Message Service (SMS) ".
[4] 3GPP TS 23.041: "Technical realization of the Cell Broadcast Service (CBS)".
[5] 3GPP TS 24.008: "Mobile Radio Interface Layer 3 specification; Core Network Protocols;
Stage 3".
[6] 3GPP TS 24.011: "Short Message Service (SMS) support on mobile radio interface".
[7] 3GPP TS 24.012: "Cell Broadcast Service (CBS) support on the mobile radio interface".
[8] 3GPP TS 27.001: "General on Terminal Adaptation Functions (TAF) for Mobile Stations (MS)".
[9] 3GPP TS 27.007: "AT command set for User Equipment (UE)".
[10] 3GPP TS 51.011: "Specification of the Subscriber Identity Module - Mobile Equipment
(SIM - ME) interface".
[11] ITU-T Recommendation V.25ter: "Serial asynchronous automatic dialling and control".
[12] ITU-T Recommendation V.24: "List of definitions for interchange circuits between data terminal
equipment (DTE) and data circuit-terminating equipment (DCE)".
[13] ITU-T Recommendation E.164: "The international public telecommunication numbering plan".
[14] ITU-T Recommendation E.163: "Numbering plan for the international telephone service".
[15] 3GPP TR 21.905: "Vocabulary for 3GPP Specifications".
[16] 3GPP TS 31.102: "Characteristics of the USIM application".
0.2 Abbreviations
For the purposes of the present document, the abbreviations given in 3GPP TR 21.905 [15] and the following]
apply.
EVPF Enhanced Validity Period Format
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1 Reference configuration
MT
TE ME
USIM
UE
Figure 1: Reference configuration
The User Equipment (UE) consists of the mobile equipment (ME) and the (U)SIM. Messages may be stored in either,
but the present document does not distinguish between messages stored in the (U)SIM or in the ME. The management
of message storage in the two parts of the UE is a matter for the UE implementation.
1.1 V.24 Interface Circuits
The operation of the ITU-T Recommendation V.24 blue book interface circuits for SMS is shown in table 1.1.
Table 1.1: Use of V.24 interface circuits
V.24 CIRCUIT DESCRIPTION TE to MT MT to TE
CT102 signal ground x x
CT103 TXD x
CT104 RXD x
CT105 RTS x
CT106 CTS x
CT107 DSR x
CT108.2 DTR x
CT109 DCD x
NOTE: CT105 at the TE is connected to CT133 at the MT.

1.1.1 Circuit definitions for the SMS Block mode
CT103
All commands from the TE to the MT are transferred across this circuit. Inband flow control is not permitted during
Block Mode.
CT104
All responses/indications from the MT to the TE are transferred across this circuit. Inband flow control is not permitted
during Block Mode.
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CT105
This circuit allows the TE to flow control the MT when in the Block Mode and at other times if hardware flow control
is enabled.
CT106
This circuit allows the MT to flow control the TE when in the Block Mode and at other times if hardware flow control
is enabled.
CT107
This circuit shall be set to the ON condition before entry into the Block Mode, and shall remain in the ON condition
during Block Mode. If the TE detects that this circuit returns to the OFF condition during the block mode then the TE
shall return CT108.2 to the OFF condition and exit the Block Mode.
CT108.2
This circuit shall be set in the ON condition before the AT+CESP command is sent from the TE to begin the Block
Mode, and shall be maintained in the ON condition during the Block Mode. It shall be returned to the OFF condition
after the command 'END SMS MODE' has been accepted and acknowledged by the MT. If the MT detects that this
circuit returns to the OFF condition during the Block Mode then the MT shall exit the Block Mode.
CT109
This circuit shall be set to the ON condition before entry into the Block Mode and remain in the ON condition during
the Block Mode. If the TE detects that this circuit returns to the OFF condition during the Block Mode then the TE shall
return CT108.2 to the OFF condition and shall exit the Block Mode.
1.1.2 Circuit definitions for the SMS Text and PDU modes
Only circuits CT102, CT103 and CT104 are mandatory for the Text and PDU modes. The functionality and operation
of other circuits shall be in accordance with V.25ter.
2 SMS Block Mode
2.1 Beginning and ending of SMS/CBS Block Mode
2.1.1 Beginning SMS/CBS Block Mode
As described in 3GPP TS 27.001 [8], the DTE/DCE interface is normally associated with the terminal adaptation
function (TAF), if such a function is available. When no data connection is in progress, and the terminal equipment
wishes to enter SMS/CBS mode, the command 'AT+CESP' shall be issued by the TE through the DTE/DCE interface
requesting that the Block mode protocol described in the present document is to be used. The syntax of this command is
further described in clause 3.2.4 later. The syntax for these commands is derived from ITU-T Recommendation V.25ter,
i.e. the command is encoded as an IA5 character string together with delimiters as described in ITU-T Recommendation
V.25ter.
Upon receipt of this command, the mobile termination shall respond as follows:
- If the mobile termination supports SMS/CBS block mode commands, responses and indications as described in
the present document, it shall respond with 'OK' (or 0) and enter the SMS/CBS mode.
- If the mobile termination does not support SMS/CBS block mode commands, responses and indications as
described in the present document, it shall respond with 'ERROR' (or 4) and remain in the current mode.
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- Terminal software shall wait a short time (e.g. 5 seconds) for the 'OK' (0) or 'ERROR' (4) response. If neither
response is received before the timeout then the terminal software shall assume that the block mode has been
entered. The terminal software may then submit its first block mode command. If no response is received to this
command then the terminal software shall proceed as described below in clause 2.2 (i.e. repeat the command 3
times and then exit the block mode).
If the SMS/CBS block mode command is accepted by the mobile termination, then all further commands, responses and
indications shall be as defined in clause 2 of the present document. These SMS/CBS mode commands, responses and
indications use 8-bit encoded data and not IA5 characters.
2.1.2 Returning from SMS/CBS Block Mode To Default Mode
When the terminal equipment wishes to return to default mode from SMS/CBS mode, it shall issue the command 'END
SMS MODE', described in clause 2.4.1.11. The mobile termination shall respond with 'OK' (or 0) to indicate that the
DTE/DCE interface has returned to default mode. The TE shall change back to default mode whether or not such a
response is received.
The TE may also indicate that it has exit from the SMS/CBS mode through the use of CT 108/2 (see clause 1.1)
If an incoming data call arrives while the DTE/DCE interface is set to SMS/CBS mode, then the mobile termination
may autonomously issue the 'END SMS MODE' indication (clause 2.4.2.11) and revert to default mode in order to
connect the data call through the TAF.
The MT may exit from SMS/CBS mode autonomously if the power to the MT is switched off and then on again. In
addition, the MT manufacturer may provide MMI to change the mode back to the default mode. In the latter case, the
MT shall issue the 'END SMS MODE' indication (clause 2.4.2.11) and exit the SMS/CBS mode immediately.
The MT may also indicate that it has exit from the SMS/CBS mode through the use of CT 107 and
CT 109 (see clause 1.1).
A BREAK condition in either direction at the DTE/DCE interface shall cause the TE and the MT to exit from the
SMS/CBS block mode and return to the default mode.
In the event where the TE or the MT find themselves unable to recover from a protocol error then either entity may exit
the SMS/CBS mode using any of the mechanisms described above. Confirmation of default mode operation will be
achieved through the use of AT commands and responses.
2.2 Protocol description
The communication path between the MT and the TE across the DTE/DCE interface should be quite reliable if it uses a
short wire link. However, to ensure that the low error rate does not cause malfunction, the following error protection
scheme is provided.
Each message sent from the MT to the TE or vice-versa consists of a data block (DATA) and block check sum (BCS,
see figure 2.2.1). In the following description the notation DLE, STX, NUL and ETX refer to control characters having
the values 10 02 00 and 03 hexadecimal respectively.
<-----------------DATA-----------------> <- BCS ->

DLE STX Message content DLE ETX BCS BCS
10H 02H  10H 03H MSB LSB
Figure 2.2.1: Format of DTE/DCE interface messages
The data block consists of a start transmission sequence, set to 00010000 00000010 (10 02 hex), the message content as
defined below and an end transmission sequence, set to 00010000 00000011 (10 03 hex). The least significant bit of
each octet is always transmitted first.
The block check sum is calculated at the transmitter by adding all of the octets in the message content modulo 65536.
Each bit of the 16-bit result is then inverted, and 1 is added to the answer.
During transmission of the message content and the BCS octets, any occurrence of the value 10 hex (DLE) shall result
in an additional 'stuffing' octet of value 00 hex (NUL) being transmitted immediately following the octet containing 10
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hex. This is to ensure that the start and end markers are unambiguous. The receiver shall remove stuffing octets by
discarding any octet of value 00 hex (NUL) which immediately follows an octet of value 10 hex (DLE).
After removal of any stuffing octets, the receiver can check the BCS by adding all of the octets in the message content
and the 16-bit BCS modulo 65536. The correct result is 0000 hex. If any message is received with an incorrect BCS,
then the message is discarded. No response is sent over the DTE/DCE interface, but an indication may be provided to
higher layers within the receiving entity.
The transmitter shall only send DLE when it is followed by STX, NUL or ETX. Therefore, if the receiver sees a DLE
followed by anything else then the receiver shall assume that some data has been lost, and shall start to search for the
start marker. An unexpected end marker at the receiver shall also result in a search for a start marker. A start marker
shall always be treated as the start of a new block, regardless of which state the receiver is in.
Examples of state diagrams for a block receiver to implement this procedure are given in Annex B, together with an
example of coding and decoding a message.
Only one Command/Response transaction shall be permitted at any one time from any sending or receiving entity. It
shall however be possible for a Command/Response transaction from one entity to be initiated even if there is a
Command/Response transaction in progress from the other entity.
If an immediate response is expected to a message sent over the DTE/DCE interface, then the sending entity shall wait
10 s. If no response is received within this time, the sending entity shall repeat the message. The message shall be
repeated a maximum of 3 times, after which the sending entity shall exit from the SMS/CBS mode and provide an error
indication to the user.
If a message cannot be understood by the receiving entity even though it has a correct BCS, then it shall return an
UNABLE TO PROCESS message with cause value 'Command not understood'. The receipt of an UNABLE TO
PROCESS message should not in itself initiate re-transmission although re-transmission may take place due to the
timeout mechanism described earlier since an UNABLE TO PROCESS is deemed to be an invalid response. The
'Cause' may however be referred to a higher layer. An UNABLE TO PROCESS shall not be sent as the result of an
incorrect BCS.
2.3 Requesting messages already held in the Mobile
Termination
The TE may request the MT to provide SMS or CBS messages already stored. The TE will either request all messages,
or request a list of messages and subsequently ask for specific messages.
At the start of the SMS/CBS mode session, the MT shall number all messages contiguously, starting with message
number 1. These "Short Message References" are only valid for a single SMS/CBS MODE session and should not be
confused with the 3GPP TS 23.040 [3] TP-Message-Reference. Each message retains its Short Message Reference for
the duration of the SMS/CBS mode session. New messages will normally be given the lowest previously-unused Short
Message Reference. However, if all Short Message References have been used then the MT may reallocate Short
Message References previously allocated to now-deleted messages.
Short Message Reference 0 signifies that there are no messages in the MT. The value of 0 is used under the following
conditions:
- When an INSERT SMS command is used to transfer an SM over the air interface and not store it in the MT then
the MT will return a Short Message Reference of 0 in the REQUEST CONFIRMED response and the ensuing
INSERT SMS COMPLETE / INSERT SMS FAILURE indications.
- For Class 0 SM's which are not stored in the MT.
- For TE specific SM's which are not stored in the MT.
If Message number 0 is requested by the TE, the MT will always return an error cause, but will also include the highest
valid Short Message Reference (see clause 2.3.2.1).
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2.3.1 Requesting List Of Messages
The TE may request the MT to provide a list of SMS and CBS messages currently stored in the mobile termination.
This is achieved by the LIST REQUEST command (clause 2.4.1.1). The MT divides the messages stored into groups of
5 (called pages) and transfers the first 5 in a MESSAGE LIST response (clause 2.4.2.1) containing message references
allocated by the MT, plus the relevant header information described in 3GPP TS 23.040 [3] and 3GPP TS 24.011 [6]
and 3GPP TS 23.041 [4] and 3GPP TS 24.012 [7].
If there are no messages stored in the MT, then the MESSAGE LIST response shall be empty.
The TE may then request further groups of up to 5 messages by repeating the LIST REQUEST command for pages 2, 3,
and so on. The MT will indicate that there are no more pages by responding with an empty MESSAGE LIST response.
2.3.2 Requesting Transfer Of Messages
The TE may request the transfer of one or more messages by means of the commands described below. The MT does
not delete messages which have been transferred. Messages can only be deleted by the DELETE MESSAGE command
(clause 2.4.1.9).
2.3.2.1 Requesting Transfer Of A Specific Message
The TE may request the MT to transfer a specific message by sending the GET MESSAGE command (clause 2.4.1.2),
including the appropriate message reference. The MT will provide the full message including header in a MESSAGE
response (clause 2.4.2.2). If the message reference is unallocated, then the GET MESSAGE FAILURE response is
returned with cause 'No such message' and the highest valid Message Reference (clause 2.4.2.3).
2.3.2.2 Requesting Transfer Of All Messages
The TE may request the MT to transfer all messages by sending the GET FIRST MESSAGE command (clause 2.4.1.3),
followed by the appropriate number of GET NEXT MESSAGE commands (clause 2.4.1.4).
The MT shall be able to transfer all messages one-by-one, starting with the 'first' and continuing with the 'next'. The
precise ordering of the messages is left to the MT implementation.
If the MT exits from SMS/CBS mode for any reason, then this information need not be retained.
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