All AT Commands GSM

What are AT commands?

AT commands are commands which are used to control the modems where AT stands for Attention. These commands were derived from Hayes commands which were used by the Hayes smart modems. Every wireless as well as the dial up modems require an AT command to interact with a computer machine. These AT commands along with other extended commands also require Hayes command set as a subset.

Usage

The AT commands can be used with GSM and GPRS MODEMs or phone to access these services and information:  SMS    ,MMS    ,Fax  

Voice link and other data over mobile network , Information and configuration concerning the mobile devices or MODEM and SIM card.

Types of AT Command
There are 4 basic types of AT commands:

1 Test: The test command is utilized to check the compatibility of a command by a                        modem.

                          SYNTAX: AT=?

2. Read: Read command is used for extracting the mobile or modem settings required 
               for operations.

                          SYNTAX: AT?

3. Set: This commands is used to make changes into mobile phone or modem settings                   required for the operation.

                         SYNTAX: AT=value1, value2, …, valueN

4. Execution: As the name suggests, this command is used to execute the said 
                      operation.

                        SYNTAX: AT=parameter1, parameter2, …, parameterN

List of AT Commands

Testing:
Command		Description
AT		Checking communication between the module and computer.
Call control:
Command	Description
ATA	Answer command
ATD	Dial command
ATH	Hang up call
ATL	Monitor speaker loudness
ATM	Monitor speaker mode
ATO	Go on-line
ATP	Set pulse dial as default
ATT	Set tone dial as default
AT+CSTA	Select type of address
AT+CRC	Cellular result codes
Data card Control:
Command		Description
ATI		Identification
ATS		Select an S-register
ATZ		Recall stored profile
AT&F		Restore factory settings
AT&V		View active configuration
AT&W		Store parameters in given profile
AT&Y		Select Set as power up option
AT+CLCK		Facility lock command
AT+COLP		Connected line identification presentation
AT+GCAP		Request complete capabilities list
AT+GMI		Request manufacturer identification
AT+GMM		Request model identification
AT+GMR		Request revision identification
AT+GSN		Request product serial number identification (IMEI)
Phone control:
Command		Description
AT+CBC		Battery charge
AT+CGMI		Request manufacturer identification
AT+CGMM		Request model identification
AT+CGMR		Request revision identification
AT+CGSN		Request product serial number identification
AT+CMEE		Report mobile equipment error
AT+CPAS		Phone activity status
AT+CPBF		Find phone book entries
AT+CPBR		Read phone book entry
AT+CPBS		Select phone book memory storage
AT+CPBW		Write phone book entry
AT+CSCS		Select TE character set
AT+CSQ		Signal quality
Computer data interface:
Command		Description
ATE		Command Echo
ATQ		Result code suppression
ATV		Define response format
ATX		Response range selection
AT&C		Define DCD usage
AT&D		Define DTR usage
AT&K		Select flow control
AT&Q		Define communications mode option
AT&S		Define DSR option
AT+ICF		DTE-DCE character framing
AT+IFC		DTE-DCE Local flow control
AT+IPR		Fixed DTE rate
Service:
Command		Description
AT+CLIP		Calling line identification presentation
AT+CR		Service reporting control
AT+DR		Data compression reporting
AT+ILRR		DTE-DCE local rate reporting
Network Communication parameter:
Command		Description
ATB		Communications standard option
AT+CBST		Select bearer service type
AT+CEER		Extended error report
AT+CRLP		Radio link protocol
AT+DS		Data compression
Miscellaneous:
Command		Description
A/		Re-execute command line
AT?		Command help
AT*C		Start SMS interpreter
AT*T		Enter SMS block mode protocol
AT*V		Activate V.25bis mode
AT*NOKIATEST		Test command
AT+CESP		Enter SMS block mode protocol
SMS Text mode:
Command		Description
AT+CSMS		Select message service
AT+CPMS		Preferred message storage
AT+CMGF		Message format
AT+CSCA		Service centre address
AT+CSMP		Set text mode parameters
AT+CSDH		Show text mode parameters
AT+CSCB		Select cell broadcast message types
AT+CSAS		Save settings
AT+CRES		Restore settings
AT+CNMI		New message indications to TE
AT+CMGL		List messages
AT+CMGR		Read message
AT+CMGS		Send message
AT+CMSS		Send message from storage
AT+CMGW		Write message to memory
AT+CMGD		Delete message
SMS PDU mode:
Command		Description
AT+CMGL		List Messages
AT+CMGR		Read message
AT+CMGS		Send message
AT+CMGW		Write message to memory

Most Commonly Used AT Commands

The below 7 are the most commonly used AT commands:

1 AT : Used to check the interaction between the computer and the module. This command is usually replied with an OK if the port and the module can connect correctly, else wise it comes back with a result code ERROR.

2. +CMGF : Used to setup the SMS mode. By adding 1 or 0 with the command text or PDU mode can be selected. Here the text mode is easy to operate although it only allows a few limited features of SMS. Where as the PDU mode allows a more detailed access to the SMS service, although to use this you require some basic knowledge of TDPU.

                 SYNTAX: AT+CMGF=<mode>

3. +CMGS : Used to send SMS to a particular phone number

                  SYNTAX: AT+CMGS= serial number of message to be send.

4. ATD : Used to make call to a particular number

              SYNTAX: ATD;(Enter)

5. ATA : Used to answer the incoming calls. The calls are denoted by a message 

              ‘RING’ which duplicated for every ring of the call. After the call ends a

              message saying ‘NO CARRIER’ is displayed.

              SYNTAX: ATA(Enter)

6. +CMGW: Used to store a message in the SIM. After the execution of the command,

                  the ‘>’ sign appears in the next line where the message can be entered.

                  SYNTAX: AT+CMGW=” Phone number”> Message to be stored Ctrl+z

7. ATH : this commaned is utilized to disconnect a remote user with the GSM module.

              SYNTAX: ATH (Enter)