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Chapter 4 – General AT Commands
Multi-Tech Systems, Inc. Wireless GSM/GPRS AT Commands (Document Number S000293I) 16
Power Off +CPOF
Description: Stops the GSM software stack as well as the hardware layer or modem activity. The AT+CFUN=0
command is equivalent to +CPOF.
Values: No parameters
Syntax: AT+CPOF[=1]
Command Possible responses
AT+CPOF
Note: Stop GSM stack
OK
Note: Command valid
AT+CPOF=1
Note: Stop the modem
OK
Note: Command valid
Note: After AT+CPOF[=1], the modem will not respond to AT commands. To reset it, use the hard
reset.
Note: I n autobaud mode, after an AT+CPOF, unsolicited information that wakes up the modem is
sent at 9600 bps until an AT command is sent. When an AT command is sent, the modem
will synchronize to the sender’s speed.
Caution: When starting up, if autobauding is enabled and no AT command has yet been received, the
product sends all unsolicited responses (like RING) at 9600 baud.
Set Phone Functionality +CFUN
Description: Selects the mobile station’s level of functionality. When the application wants to stop the product with a
power off, or if the application wants to force the product to execute an IMSI DETACH procedure, then it
must send: AT+CFUN=0 (equivalent to AT+CPOF).
This command executes an IMSI DETACH and makes a backup copy of some internal parameters in
SIM and in EEPROM. The SIM card cannot then be accessed.
If the mobile equipment is not powered off by the application after this command has been sent, a re-
start command (AT+CFUN=1) will have to issued to restart the whole GSM registration process.
If the mobile equipment is turned off after this command, then a power on will automatically restart the
whole GSM process.
The AT+CFUN=1 command restarts the entire GSM stack and GSM functionality: a complete software
reset is performed. All parameters are reset to their previous values if AT&W was not used.
If you write entries in the phonebook (+CPBW) and then reset the product directly (AT+CFUN=1, with
no previous AT+CFUN=0 command), some entries may not be written (the SIM task does not have
enough time to write entries in the SIM card).
In addition, the OK response will be sent at the last baud rate defined by the +IPR command. With the
autobauding mode the response can be at a different baud rate, it is therefore preferable to save the
defined baud rate with AT&W before directly sending the AT+CFUN=1 command.
Values: <functionality level>
0 Set minimum funtionality; IMSI detach procedure
1 Set the full functionality mode with a complete software reset
Syntax: AT+CFUN=<functionality level>
Command Possible responses
AT+CFUN?
Note: Ask for current functionality level
+CFUN: 1
OK
Note: Full functionality
AT+CFUN=0
Note: Set minimum functionality, IMSI detach procedure
OK
Note: Command valid
AT+CFUN=1
Note: Set the full functionality mode with a complete software reset
OK
Note: Command valid