1 Reference configuration

07.053GPPTSUse of Data Terminal Equipment - Data Circuit Terminating Equipment (DTE-DCE) Interface for Short Message Services (SMS) and Cell Broadcast Services (CBS)

MOBILE TERMINATION (MT2)

Figure 1: Reference configuration

The mobile termination consists of the mobile equipment (ME) and the SIM. Messages may be stored in either, but this specification does not distinguish between messages stored in the SIM or in the ME. The management of message storage in the two parts of the mobile termination is a matter for the mobile termination implementation.

1.1 V.24 Interface Circuits

The operation of the CCITT V.24 blue book interface circuits for SMS is shown in table 1.1/GSM 07.05.

Table 1.1/GSM 07.05: 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.

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.