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Global System for Mobile communications

The Protocol Identifier octet


The TP-Protocol-Identifier parameter consists of one octet, and the bits in the octet are used as follows: The MS will interpret reserved or unsupported values as the value 00000000 but shall store them exactly as received. The SC may reject messages with a TP-Protocol-Identifier containing a reserved value or one which is not supported.

Bit 7 Bit 6 Usage
0 0 Assigns bits 0..5 as defined below
0 1 Assigns bits 0..5 as defined below
1 0 Reserved
1 1 Assigns bits 0..5 for SC specific use
In case where bits 7 and 6 both are 0:
Bit 5 Description
0 no interworking, but SME-to-SME protocol
1 telematic interworking
In the case of telematic interworking, the following five bit patterns in bits 4..0 are used to indicate types of telematic devices:
Bits 4..0 Description
00000 implicit - device type is specific to this SC, or can be concluded on the basis of the address
00001 telex (or teletex reduced to telex format)
00010 group 3 telefax
00011 group 4 telefax
00100 voice telephone (i.e. conversion to speech)
00101 ERMES (European Radio Messaging System)
00110 National Paging System (known to the SC)
00111 Videotex (T.100/T.101)
01000 teletex, carrier unspecified
01001 teletex, in PSPDN
01010 teletex, in CSPDN
01011 teletex, in analog PSTN
01100 teletex, in digital ISDN
01101 UCI (Universal Computer Interface, ETSI DE/PS 3 01-3)
(reserved, 2 combinations)
10000 a message handling facility (known to the SC)
10001 any public X.400-based message handling system
10010 Internet Electronic Mail
(reserved, 5 combinations)
values specific to each SC, usage based on mutual agreement between the SME and the SC (7 combinations available for each SC)

A GSM mobile station. The SC converts the SM from the received TP-DCS to any data coding scheme supported by that MS (e.g. the default).

If bit 5 has value 1 in an SMS-SUBMIT PDU, it indicates that the SME is a telematic device of a type which is indicated in bits 4..0, and requests the SC to convert the SM into a form suited for that device type. If the destination network is ISDN, the SC must also select the proper service indicators for connecting to a device of that type.

If bit 5 has value 1 in an SMS-DELIVER PDU, it indicates that the SME is a telematic device of a type which is indicated in bits 4..0.

If bit 5 has value 0 in an SMS-DELIVER PDU, the value in bits 4..0 indicates the SM-AL protocol being used between the SME and the MS.

Note that for the straightforward case of simple MS-to-SC short message transfer the Protocol Identifier is set to the value 0.

In the case where bit 7 = 0, bit 6 = 1, bits 5..0 are used as defined below
Bits 5..0 Description
000000 Short Message Type 0
000001 Replace Short Message Type 1
000010 Replace Short Message Type 2
000011 Replace Short Message Type 3
000100 Replace Short Message Type 4
000101 Replace Short Message Type 5
000110 Replace Short Message Type 6
000111 Replace Short Message Type 7
001000..011110 Reserved
011111 Return Call Message
100000..111100 Reserved
111101 ME Data download
111110 ME De-personalization Short MEssage
111111 SIM Data download

A short message type 0 indicates that the ME must acknowledge receipt of the short message but may discard its contents.

The Replace Short Message feature is optional for the ME and the SIM but if implemented it shall be performed as descriped here.

For MT short messages, on receipt of a short message from from the SC, the MS shall check to see if the associated Protocol Identifier contains a Replace Short Message Type code.

If such a code is present, the the MS will check the originating address and replace any existing stored message having the same Protocol Identifier code and originating address with the new short message and other parameter values. If there is no message to be replaced, the MS shall store the message in the normal way. The MS may also check the SC address as well as the Originating Address. However, in a network which has multiple SCs, it is possible for a Replace Message type for a SM to be sent via different SCs and so it is recommended that the SC address should not be checked by the MS unless the application specifically requires such a check.

If a Replace Short Message Type code is not present then the MS will will store the message in the normal way.

In MO short messages the SC reacts similarly but only the address of the originating MS or any other source is checked.

A Return Call Message indicates to the MS to inform the user that a call (e.g. a telephone call) can be established to the address specified within the TP-OA. The RP-OA contains the address of the SC as usual. The message content (if present) gives displayable information (e.g. the number of waiting voice messages). The message is handled in the same way as all other messages of the Replace Short Message Types.

The ME De-personalization Short Message is an ME-specific message which instructs the ME to de-personalities the ME (see GSM 2.22). The TP-DCS shall be set to Uncompressed, Default Alphabet, and Message Class 1 (Me-specific), which corresponds to a bit coding og 00010001. The TP-UD field contains de-personalization information coded according to GSM 02.22. This information shall not be displayed by an ME which supports the scheme. The acknowledgement to this message is a SMS-DELIVER-REPORT for RP-ACK in ehich the TP-User-Data shall be coded according to GSM 02.22.

SIM Data download is a facility whereby the ME must pass the short message in its entirety including all SMS elements contained in the SMS deliver to the SIM using the mechanism descriped in GSM 11.11. The DCS shall be set to 8 bit message class 2 (either bit coding 11110110 or 00010110). The entire user data field is available for SIM Data download.

ME Data download is facility whereby the ME shall process the short message in its entirety including all SMS elements contained in the SMS deliver to the ME. The DCS shall be set to message class 1. The entire user data field is available for ME data download.