SS information introduction

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SMS

3GPP TS 24.011 http://www.etsi.org

The Short Message Service (SMS) is used to transfer text messages over mobile networks between a GSM PLMN Mobile Station and a Short Message Entity via a Service Center. The terms MO (Mobile Originating) and MT (Mobile Terminating) are used to indicate the direction in which the short message is sent.
SMS messages can be encapsulated in control or relay messages.

SMS Control Message
The format of the control protocol message header is shown in the following illustration:

8	7	6	5	4	3	2	1	Octet
Protocol discriminator				Transaction identifier				1
Message type								2
Information elements								3-n
SMS control protocol header structureheader structure

Protocol discriminator
1001 identifies the SMS protocol.

Transaction identifier
The transaction identifier (TI) distinguishes multiple parallel activities (transactions) within one mobile station. The format of the transaction identifier is as follows:

4	3	2	1
TI flag	TI value			- - - -
Transaction identifier

TI flag
Identifies who allocated the TI value for this transaction. The purpose of the TI flag is to resolve simultaneous attempts to allocate the same TI value.

TI value
TI values are assigned by the side of the interface initiating a transaction. At the beginning of a transaction, a free TI value is chosen and assigned to this transaction. It then remains fixed for the lifetime of the transaction. After a transaction ends, the associated TI value is free and may be reassigned to a later transaction. Two identical transaction identifier values may be used when each value pertains to a transaction originated at opposite ends of the interface.

Message type
The message type, together with the protocol discriminator, identifies the function of the message being sent. Messages may be of the following:

0000 0001	CP-DATA
0000 0100	CP-ACK
0001 0000	CP-ERROR

Information elements
Each IE has an identifier which is coded as a single octet. The length of an IE may be fixed or variable and may or may not include a length indicator.

SMS Relay Protocol Message
The format of the relay protocol message header is shown in the following illustration:

8	7	6	5	4	3	2	1	Octet
0	0	0	0	0				1
Message reference								2
Information elements								3-n
SMS relay protocol header structure

MTI
Message type indicator. Values are as follows:
Bit Value (3 2 1) Direction RP-Message

0 0 0	ms -> n	RP-DATA
0 0 0	n -> ms	Reserved
0 0 1	ms -> n	Reserved
0 0 1	n -> ms	RP-DATA
0 1 0	ms -> n	RP-ACK
0 1 0	n -> ms	Reserved
0 1 1	ms -> n	Reserved
0 1 1	n -> ms	RP-ACK
1 0 0	ms -> n	RP-ERROR
1 0 0	n -> ms	Reserved
1 0 1	ms -> n	Reserved
1 0 1	n -> ms	RP-ERROR
1 1 0	ms -> n	RP-SMMA
1 1 0	n -> ms	Reserved
1 1 1	ms -> n	Reserved

Message reference
Used to link an RP-ACK message or RP-ERROR message to the associated RP-Data or RP-SMMA message transfer attempt.

Information elements
Each IE has an identifier which is coded as a single octet. The length of an IE may be fixed or variable and may or may not include a length indicator.

SMS TP

ETSI TS 123 040. (You can download all the ETSI files from www.ETSI.org)

The SMS TP (Short Message Transfer Layer Protocol) is comprised of two basic services:

• SM MT (Short Message Mobile Terminated).
• SM MO (Short Message Mobile Originated).
  

SM MO denotes the capability of the GSM/UMTS system to transfer a short message submitted by the MS to one SME via an SC, and to provide information about the delivery of the short message either by a delivery report or a failure report with a specific mechanism for later delivery. The message must include the address of that SME to which the SC shall eventually attempt to relay the short Message Transfer Layer Protocol.
The text messages to be transferred by means of the SM MT or SM MO contains up to 140 octets.
The structure of the SMS TP protocol header is as follows:

8	7	6	5	4	3	2	1	Octet
Message type								1
Information Elements								2-n

Message Type
The type of message, the following message types are available:
SC To MS

0 1 2 3

SMS-DELIVER SMS-SUBMIT-REPORT SMS-STATUS-REPORT Reserved

MS To SC

0 1 2 3

SMS-DELIVER-REPORT SMS-SUBMIT SMS-COMMAND Reserved

SS

3GPP TS 24.080 http://webapp.etsi.org/key/queryform.asp

This Supplementary Services protocol defines the structure of the messages of the layer 3 protocol defined in 3GPP TS 24.080. These messages are standard L3 messages. SS is both for GPRS and for UMTS.

The structure of the header is as follows:

8	7	6	5	4	3	2	1	Octet
Protocol Discriminator				Transaction ID				1
Message type								2
Information elements								3-n

Protocol Discriminator	The Protocol discriminator (must be 0x0B).
Transaction Identifier	The format and coding of transaction identifier values.
Message Type	The Message type number.

The following message types are available

42	Release Complete
58	Facility
59	Register