22.4. Example
Demonstrating How to Use the +CPMS AT Command to Select the Message
Storage Areas to be Used
Now
let's see an example that demonstrates how to use the +CPMS AT
command to select the message storage areas to be used for various
SMS operations.
Finding
the Message Storage Areas Supported by the GSM/GPRS Modem or Mobile
Phone
First,
enter the command line "AT+CPMS=?" in a terminal program
(for example, Windows' HyperTerminal program) to find the message
storage areas supported by the GSM/GPRS modem or mobile phone. Below
shows the response returned from my Nokia 6021 to Windows'
HyperTerminal program after the execution of the command line
"AT+CPMS=?":
AT+CPMS=?
+CPMS:
("ME","SM"),("ME","SM"),("MT")
OK
The
information response above indicates Nokia 6021 supports the use of
"ME" or "SM" for SMS reading, deleting, sending
and writing, while it only supports
the use of "MT" for storing inbound SMS messages.
Selecting
Message Storage Areas
After
knowing what message storage areas are selectable, we can now
perform a set operation to select the message storage areas. For
example, let's say you want to instruct the GSM/GPRS modem or mobile
phone to use:
the
phone message storage area for SMS reading and deleting,
the
SIM message storage area for SMS writing and sending, and
both
the phone message storage area and SIM message storage area for
storing inbound SMS messages.
You
should assign the string values "ME", "SM" and
"MT" to the +CPMS AT command. Following shows the response
returned from my Nokia 6021 mobile phone to HyperTerminal:
AT+CPMS="ME","SM","MT"
+CPMS:
2,150,2,10,4,160
OK
As
you can see, there are six values in the information response of the
+CPMS AT command. Following is a description of them.
The
First and Second Fields: 2,150
The
value 2 indicates there are currently two messages stored in the ME
message storage area. 150 is the maximum number of messages that can
be stored in the ME message storage area.
The
Third and Fourth Fields: 2,10
The
value 2 indicates there are currently two messages stored in the SM
message storage area. 10 is the maximum number of messages that can
be stored in the SM message storage area.
The
Fifth and Sixth Fields: 4,160
The
value of the fifth field of the +CPMS information response, 4,
indicates there are currently four messages stored in the MT message
storage area. The same result can also be obtained by calculating
manually like this:
Number
of messages currently stored in the ME message storage area + Number
of messages currently stored in the SM message storage area
= 2 +
2
= 4
The
value of the sixth field of the +CPMS information response, 160, is
the maximum number of messages that can be stored in the MT message
storage area. The same result can also be obtained by calculating
manually like this:
Maximum
number of messages that can be stored in the ME message storage area
+ Maximum number of messages that can be stored in the SM message
storage area
= 150 + 10
= 160
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