Technical reference section
Setting up and clearing down connections
Once you have read through this section, you will be able to use your GSM module to- gether with your communication program to perform the following functions:
•Interrupt a connection using the escape command.
•Go
•Set up a connection by manually dialing the telephone number.
•Store a telephone number.
•Dial a stored telephone number.
•Answer a call.
•Switch to
Operating modes
The GSM module operates in two different modes:
•Command mode
•Transparent mode
Command mode
When you switch on your system, the GSM module is in command mode and is ready to receive and execute your commands. All characters that the GSM module receives via the COM interface in this mode are interpreted as commands and, if a phone con- nection is present, are not transferred to the distant station.
Transparent mode
In transparent mode, the GSM module transfers every character sent and received via the COM interface just as it is.
Escape command
Before attempting to dial your first call, you must know how to interrupt or disconnect a call at any time. This involves the following two steps:
•Enter to switch to command mode.
•Disconnect the call by entering ATH.
Example:
Situation: The GSM module is operating in transparent mode, i.e. a connection is set up to a distant station.
Change to command mode:
•Do not press any key for at least one second.
•Press the key three times in rapid succession (within one second).
•Do not press another key for at least one second.
The GSM module switches to command mode, i.e. it interrupts the flow of data and
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