SMS Dispatch Manager

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Modem AT Commands

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+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