User`s guide

Chapter 1 – AT Commands for Remote SIM Application Toolkit
Multi-Tech Systems, Inc. SIM Application Toolkit AT Commands (S000391C) 5
1.1.3 SAT Context Diagram
1.1.4 Usage of Remote-SAT
Remote-SAT (RSAT) is designed as an AT interface which establishes the link between the SIM application running
on the SIM card and the customer application (PDA, laptop, etc.). The purpose of RSAT is to allow the customer
application to issue AT commands to the SAT interface and to display all SAT activities on the user interface of the
customer application. To take advantage of Remote-SAT it must be explicitly started using the AT^SSTA command.
If no customer application is involved, there is no need to communicate through the AT interface, and the Remote-
SAT can be ignored. In this case, all commands and responses may be exchanged directly between the module's
SAT interface and the GSM network.
Both scenarios – whether or not Remote-SAT is activated – are illustrated in the context diagram in section 1.1.3.
As a cellular module does not have an MMI, Remote-SAT differs from a phone implementation of SAT. It uses a
special set of AT Commands to pass data; e.g., a list of menu items, to the TA and to receive responses; e.g., a
selected menu item.
The TA, being the customer application, is required to implement a state machine that controls the module's SAT. It
monitors the states of SAT and, if required, sends appropriate AT commands depending upon user’s input.
The implementation of the Remote-Sat AT commands is not necessary if the customer application does not offer the
SIM Application Toolkit to the end user. Therefore, the state machine and the use of Remote-SAT AT commands do
not need to be implemented in the TA.
1.1.5 Command Type Values
The Command Type Value (<cmdType>) identifies the type of command or associated response passed between
the TA (customer application) and the ME.
<cmdType>) is the parameter that comes first in AT commands, in response to AT^SSTGI (see Chapter 1.4) and
AT^SSTR (see Chapter 1.5), and in the ^SSTN unsolicited result code (see Chapter 1.3).
The SAT implementation supports SAT class 3 (GSM 11.14 Release 98, letter class “c”).
Table 1 summarizes only those command types and parameters which may appear on the user interface (UI) and
thus, allow the user to take an action. Command types that are transparent to the user are not listed in the table,
although they are supported by Remote-SAT as specified in GSM 11.14.