SIM Application Toolkit

SIM Application Toolkit

Have you ever use Mobile Banking menu in your Mobile Phone ? In your Mobile Phone there are some interactive menus which let your Mobile Phone 'talk' with the network. This menus displayed in your Mobile Phone screen in a 'scroll down' menu. By entering one menu, then you will come into the sub menus. This capability is provided by two direction communication between SIM Card and Mobile Phone and just a part of mechanism named SIM Application Toolkit (SAT). SAT provide mechanism which reside in the SIM Card to communnicate and interact with Mobile Phone. SAT action is initiated by Mobile Phone. SAT can only work during the network operation phase of GSM.

Some simple facts of SAT are :

- SAT applications is a set of commands inside SIM Card which define how the SIM Card interact with the outside world through Mobile Phone.

- SAT is designed as client server application. SIM Card act as a client and network act as a sever. As A server, network provide services to SIM Card which previously asked by the SIM Card. If the SIM Card indicating that it support SAT commands, then Mobile Phone will execute the next command.

- Mobile Phone act as interface to trigger SAT commands.

- SIM Card send command to Mobile Phone in TLV format.

SAT Mechanism

Profile Download

This mechanism allow MObile Phone to ask to SIM Card what SAT capability it can provide. The Mobile Phone knows SIM Card SAT capability by reading EF Phase. One of the initialization steps on the Mobile Phone is by reading this EF. By using initialization, a Mobile Phone can get information about capabilities those can be provided by SIM Card inside it.

Proactive SIM

Proactive SIM give order mechanism to the SIM Card so it can ask Mobile Phone to execute certain actions. These actions include :

- Displaying text from SIM Card to Mobile Phone's screen.
- Sending a Short Message
- Make a voice call to a number that held by the SIM Card.
- Make a data call to a number and bearer capabilities that held ny the SIM Card.
- Playing tone.
- Provide a dialogue with the user.
- SIM initialization request and change notification to EFs.
- Provide local information from the Mobile Phone to the SIM Card.

Data Download to SIM

This command allow network to use SMS or cell broadcast to transfer information to the SIM Card.
Information transfer over SIM- ME uses the ENVELOPE command. If the Mobile Phone receive SMS with
protocol identifier equal to SIM Data Download and coding scheme equals to class 2 message, then the Mobile Phone will pass the SMS directly to the SIM Card without intervension of Mobile Phone's user.

Menu Selection

A set of menu entries is provided by the SIM Card in Proactive SIM command. The menu shows some menu applications so the user can enter the menu appliaction and then this menu selection will transfer command to the SIM Card.

Call Control by the SIM

When this SAT service activated in a Mobile Phone, whena user make a call, it will result in a phone number, supplementary service, and unstructured supplementary service data (USSD) strings first sent to the SIM Card. The SIM Card can decide wether it will alow this action or selectively bar it.

Mobile Originated Short Message Control by SIM

This SAT service use the same mechanism like Call Control. But this service applied to the SMS. Before a Mobile Phone sending any SMS, it will ask SIM Card authorization. The SIM Card will return with an answer which can be authorization or refusal.

Event Download

A set to monitor for is supplied by SIM Card in proactive SIM command. This mechanism is used to transfer details of event to the SIM. Events that a Mobile Phone can report to the SIM card area include incoming calls, location status, and availability of the screen for applications.

Security

Multiple Card

One event and a set of proactive commands are supplied to monitor card behaviour.

Timer Expiration

SIM Card has capability to manage timers which running physically in the Mobile Phone with proactive command. This mechanism is used to inform the SIM when a timer exprires.

Bearer Independent Protocol

Reference : 3GPP TS 11.14 , Specification of SIM Application Toolkit (SAT) for the SIM -ME Interface