17.2. Set Command -- Changes the Settings Used for Certain Tasks

A set operation changes the settings used by the GSM/GPRS modem or mobile phone for certain tasks. The syntax is:

command=value1,value2,...valueN

where command is an AT command and value1 to valueN are the values you want to set. When an AT command is used in the above syntax to perform a set operation, it is called a set command.

Here is an example. The AT command +CSCA (command name in text: Service Centre Address) is used to set the SMSC (SMS center) address for sending SMS messages. It takes two parameters that specify the SMSC address and type of address. To set the SMSC address to +85291234567, enter the following command line in a terminal program such as MS Windows' HyperTerminal:

AT+CSCA="+85291234567",145

If the set command runs successfully, the result code "OK" will be returned:

AT+CSCA="+85291234567",145
OK

Some AT commands have optional parameters. You can choose not to assign values to them. For example, the second parameter of the +CSCA AT command is optional. If no value is assigned to the second parameter, the GSM/GPRS modem or mobile phone will use the default parameter value, which is 145 if the SMSC address starts with "+" (the plus character). Hence, this command line:

AT+CSCA="+85291234567"

is equivalent to:

AT+CSCA="+85291234567",145

Typically the values you specified with set commands are placed in volatile memory. If the GSM/GPRS modem or mobile phone is switched off or rebooted, the values you specified with set commands will be gone. When the GSM/GPRS modem or mobile phone is powered on again, all settings are back to the defaults.

For some commonly used settings, there are AT commands for saving/restoring the settings to/from non-volatile memory. For example, the AT commands +CSAS (command name in text: Save Settings) and +CRES (command name in text: Restore Settings) can be used to save and restore settings related to SMS messaging such as the SMS center address.

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