The categories of control commands are:
General Commands (GSM 07.07, section 5)
Command |
Description |
AT+CGMI |
Identify manufacturer |
AT+CGMM |
Identify model |
AT+CGMR |
Identify revision |
AT+CGSN |
Identify serial number (of device, not SIM card) |
AT+CSCS |
Select character set |
Call Control Commands (GSM 07.07, section 6)
Command |
Description |
ATDnnn; |
Dial "nnn" in voice mode. |
ATH |
Hangup the current call. |
ATA |
Answer an incoming call. |
Note: When the ATD command is used with a trailing ';', it must return immediately to command mode after command processing. Some phones and modems have been known to wait until the receiving party answers the call, or busy is detected, before returning to command mode. Such phones and modems are not compliant with the GSM specification.
The GSM specification permits ATD to be used in a special mode for dialing directly from phone books.
It is important that ATD recognize numbers starting with + as international, and all other numbers as being local.
Network Services Related Commands (GSM 07.07, section 7)
Command |
Description |
AT+CNUM |
Subscriber number |
AT+CREG |
Network registration |
AT+COPS |
Operator selection |
AT+CLCK |
Facility lock |
AT+CPWD |
Change password |
AT+CLIP |
Enable caller line identification |
AT+CLIR |
Caller ID restriction |
AT+CCUG |
Closed user group |
AT+CCFC |
Call forwarding number and conditions |
AT+CCWA |
Call waiting |
AT+CHLD |
Call hold and multiparty |
AT+CTFR |
Call transfer |
AT+CAOC |
Advice of charge |
Mobile Equipment Control and Status Commands (GSM 07.07, section 8)
Command |
Description |
AT+CPAS |
Phone activity status |
AT+CFUN |
Set phone functionality |
AT+CPIN |
Enter PIN |
AT+CBC |
Battery charge |
AT+CSQ |
Signal quality |
AT+CPBS |
Select phone book memory storage |
AT+CPBR |
Read phone book entries |
AT+CPBW |
Write phone book entries |
The phone book commands are intended for accessing phone books stored on SIM cards, typically the SM phone book.
SMS Commands (GSM 07.05)
Command |
Description |
AT+CPMS |
Preferred message storage |
AT+CMGF |
Message format (we use format 0: PDU) |
AT+CSCA |
Service centre address |
AT+CNMI |
Enable new message indications |
AT+CSCB |
Select cell broadcast message types |
AT+CMGL |
List messages |
AT+CMGR |
Read message |
AT+CMGS |
Send message |
AT+CMGD |
Delete message |
AT+CMMS |
More messages to send |
+CMTI |
Notification of SMS message delivery. |
+CBMI |
Notification of a cell broadcast message. |
+CDSI |
Notification of an SMS status report message. |
+CBM |
Notification of a directly delivered cell broadcast message. |
It is assumed that incoming SMS messages are stored in a temporary storage area on the device and that we retrieve the messages using the AT+CMGL and AT+CMGR commands.
Multiplexing Commands (GSM 07.10)
The modem needs to support the AT+CMUX command plus the basic packet mode in GSM 07.10.
Other Commands
Command |
Description |
AT+VTS |
DTMF and tone generation (GSM 07.07, Appendix C) |
AT+CVIB |
Select vibrate mode |
AT+CPUC |
Price per unit |
AT+CIMI |
SIM identity |
AT+CHSC |
Get phone status (only needed if AT+CPAS is not available) |
AT+CLCC |
List active calls |
Phone-specific Commands
The GSM specification lacks some functionality required to provide a complete feature set. The most important of these is Call Monitoring, that is, when an outgoing dial request is made, a method of detecting call acceptance or rejection by the other party is required.
Command |
Description |
AT*ECAM |
Turn on call monitoring |
AT*ESIL |
Select silent mode |
*ECAV |
Unsolicited response for AT*ECAM |
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