26.3.7. Finding the Message Status Values Supported by the +CMGL AT Command in SMS PDU Mode

As mentioned earlier, the +CMGL AT command takes one parameter, message_status. Performing a test operation with the +CMGL AT command allows you to find all message status values that are supported by the message_status parameter. Here is the format of the information response returned after the execution of the test command "+CMGL=?":

+CMGL: (list_of_status_values)

In SMS PDU mode, the values inside the above parentheses are integers. The SMS specification has defined five message status values: 0, 1, 2, 3 and 4. They are supported by most GSM/GPRS modems and mobile phones. A description of these five message status values can be found in the earlier section "Syntax of the +CMGL AT Command in SMS PDU Mode".

As an example, here is the response returned from my Nokia 6021 mobile phone to the HyperTerminal program in Windows after the execution of the test command "+CMGL=?":

AT+CMGL=?
+CMGL: (0-4)

OK

From above, we know that the Nokia 6021 mobile phone supports all of the five message status values defined in the SMS specification.

Do you remember that we described the format of values inside parentheses in the section "Test Command -- Checks Whether a Certain AT Command is Supported"? If not, you may want to go back and have a look. Here are a few examples showing some of the possibilities: "(0-4)", "(0,1,2,3,4)", "(0,2-4)".

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