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Command

SIM900 AT Command Manual

Document Title:

SIM900 AT Command Manual

Version:

1.03

Date:

2010-12-24

Status:

Release

Document Control ID:

SIM900_AT Command Manual_V1.03

General Notes
SIMCom offers this information as a service to its customers, to support application and
engineering efforts that use the products designed by SIMCom. The information provided is based
upon requirements specifically provided to SIMCom by the customers. SIMCom has not
undertaken any independent search for additional relevant information, including any information
that may be in the customer’s possession. Furthermore, system validation of this product designed
by SIMCom within a larger electronic system remains the responsibility of the customer or the
customer’s system integrator. All specifications supplied herein are subject to change.
Copyright
This document contains proprietary technical information which is the property of Shanghai
SIMCom Wireless Solutions Ltd, copying of this document and giving it to others and the using or
communication of the contents thereof, are forbidden without express authority. Offenders are
liable to the payment of damages. All rights reserved in the event of grant of a patent or the
registration of a utility model or design. All specification supplied herein are subject to change
without notice at any time.
Copyright © Shanghai SIMCom Wireless Solutions Ltd. 2010

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Version History
Version

Chapter

What is new

V1.00

New version

Created on the basis of SIM900 AT Test Result

V1.01

3.2.50 AT+CALS
6.2.27 AT+CBTE
6.2.30 AT+STTONE
8.2.21 AT+CIPDPDP
8.2.25AT+CIPUDPMODE
6.2.45 AT+SGPIO
6.2.46 AT+SPWM
6.2.47 AT+ECHO

Add new command
Add new command
Add new command
Add new command
Add new command
Add new command
Add new command
Add new command

V1.02

3.2.16 AT+CLCC
3.2.30 AT+CR

Add write command
Add parameter GPRS

V1.03

6.2.47 AT+SPWM
6.2.48 AT+ECHO
6.2.50 AT+GSMBUSY
8.2.26 AT+CIPRXGET
8.2.27 AT+CIPQRCLOSE
8.2.28 AT+CIPSCONT
9.2.1 AT+SAPBR
10.2.x HTTP commands
11.2.x FTP commands

Modified the command
Modified the parameter scope
Add new command
Add new command
Add new command
Add new command
Add new command
Add new commands
Add new commands

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Contents
1 Introduction..................................................................................................................................11
1.1 Scope of the document .......................................................................................................... 11
1.2 Related documents ................................................................................................................ 11
1.3 Conventions and abbreviations .............................................................................................12
1.4 AT Command syntax .............................................................................................................12
1.4.1 Basic syntax ...................................................................................................................12
1.4.2 S Parameter syntax.........................................................................................................13
1.4.3 Extended Syntax.............................................................................................................13
1.4.4 Combining AT commands on the same Command line.................................................13
1.4.5 Entering successive AT commands on separate lines.....................................................13
1.5 Supported character sets........................................................................................................13
1.6 Flow control ..........................................................................................................................14
1.6.1 Software flow control (XON/XOFF flow control).........................................................14
1.6.2 Hardware flow control (RTS/CTS flow control)............................................................15
2 AT Commands According to V.25TER.......................................................................................16
2.1 Overview of AT Commands According to V.25TER ............................................................16
2.2 Detailed Description of AT Commands According to V.25TER ...........................................17
2.2.1 A/ Re-issues the Last Command Given.......................................................................17
2.2.2 ATA ANSWER AN INCOMING CALL ....................................................................17
2.2.3 ATD Mobile Originated Call to Dial A Number..........................................................18
2.2.4 ATD> Originate Call to Phone Number in Current Memory................................20
2.2.5 ATD> Originate Call to Phone Number in Memory Which Corresponds to Field
 ........................................................................................................................................21
2.2.6 ATDL Redial Last Telephone Number Used...............................................................23
2.2.7 ATE Set Command Echo Mode ..................................................................................23
2.2.8 ATH Disconnect Existing Connection.........................................................................24
2.2.9 ATI Display Product Identification Information .........................................................25
2.2.10 ATL Set Monitor speaker loudness............................................................................25
2.2.11 ATM Set Monitor Speaker Mode ..............................................................................25
2.2.12 +++ Switch from Data Mode or PPP Online Mode to Command Mode ..................25
2.2.13 ATO Switch from Command Mode to Data Mode....................................................26
2.2.14 ATP Select Pulse Dialling..........................................................................................26
2.2.15 ATQ Set Result Code Presentation Mode..................................................................26
2.2.16 ATS0 Set Number of Rings before Automatically Answering the Call.....................27
2.2.17 ATS3 Set Command Line Termination Character .....................................................27
2.2.18 ATS4 Set Response Formatting Character ................................................................28
2.2.19 ATS5 Set Command Line Editing Character.............................................................28
2.2.20 ATS6 Pause Before Blind Dialling............................................................................29
2.2.21 ATS7 Set Number of Seconds to Wait for Connection Completion..........................29
2.2.22 ATS8 Set Number of Seconds to Wait for Comma Dial Modifier Encountered in Dial
String of D Command .............................................................................................................30
2.2.23 ATS10 Set Disconnect Delay after Indicating the Absence of Data Carrier..............30
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2.2.24 ATT Select Tone Dialing ...........................................................................................31
2.2.25 ATV TA Response Format .......................................................................................31
2.2.26 ATX Set CONNECT Result Code Format and Monitor Call Progress .....................32
2.2.27 ATZ Reset Default Configuration .............................................................................32
2.2.28 AT&C Set DCD Function Mode ...............................................................................33
2.2.29 AT&D Set DTR Function Mode................................................................................34
2.2.30 AT&F Factory Defined Configuration ......................................................................34
2.2.31 AT&V Display Current Configuration ......................................................................36
2.2.32 AT&W Store Active Profile ......................................................................................36
2.2.33 AT+GCAP Request Complete TA Capabilities List ..................................................37
2.2.34 AT+GMI Request Manufacturer Identification .........................................................37
2.2.35 AT+GMM Request TA Model Identification ............................................................38
2.2.36 AT+GMR Request TA Revision Identification of Software Release.........................38
2.2.37 AT+GOI Request Global Object Identification .........................................................38
2.2.38 AT+GSN Request TA Serial Number Identification (IMEI) .....................................39
2.2.39 AT+ICF Set TE-TA Control Character Framing........................................................39
2.2.40 AT+IFC Set TE-TA Local Data Flow Control ..........................................................40
2.2.41 AT+IPR Set TE-TA Fixed Local Rate .......................................................................41
2.2.42 AT+HVOIC Disconnect Voice Call Only..................................................................42
3 AT Commands According to GSM07.07.....................................................................................43
3.1 Overview of AT Command According to GSM07.07 ...........................................................43
3.2 Detailed Descriptions of AT Command According to GSM07.07 ........................................44
3.2.1 AT+CACM Accumulated Call Meter (ACM) Reset or Query....................................44
3.2.2 AT+CAMM Accumulated Call Meter Maximum (ACM max) Set or Query .............45
3.2.3 AT+CAOC Advice of Charge .....................................................................................46
3.2.4 AT+CBST Select Bearer Service Type........................................................................47
3.2.5 AT+CCFC Call Forwarding Number and Conditions Control ....................................48
3.2.6 AT+CCWA Call Waiting Control ................................................................................49
3.2.7AT+CEER Extended Error Report ...............................................................................51
3.2.8 AT+CGMI Request Manufacturer Identification ........................................................53
3.2.9 AT+CGMM Request Model Identification..................................................................53
3.2.10 AT+CGMR Request TA Revision Identification of Software Release ......................54
3.2.11 AT+CGSN Request Product Serial Number Identification (Identical with +GSN)...54
3.2.12 AT+CSCS Select TE Character Set ...........................................................................55
3.2.13 AT+CSTA Select Type of Address ............................................................................56
3.2.14 AT+CHLD Call Hold and Multiparty........................................................................56
3.2.15 AT+CIMI Request International Mobile Subscriber Identity....................................57
3.2.16 AT+CLCC List Current Calls of ME.........................................................................58
3.2.17 AT+CLCK Facility Lock...........................................................................................60
3.2.18 AT+CLIP Calling Line Identification Presentation ...................................................61
3.2.19 AT+CLIR Calling Line Identification Restriction.....................................................62
3.2.20 AT+CMEE Report Mobile Equipment Error.............................................................63
3.2.21 AT+COLP Connected Line Identification Presentation ............................................64
3.2.22 AT+COPS Operator Selection...................................................................................66
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3.2.23 AT+CPAS Phone Activity Status...............................................................................67
3.2.24 AT+CPBF Find Phonebook Entries...........................................................................67
3.2.25 AT+CPBR Read Current Phonebook Entries ............................................................69
3.2.26 AT+CPBS Select Phonebook Memory Storage.........................................................69
3.2.27 AT+CPBW Write Phonebook Entry ..........................................................................71
3.2.28 AT+CPIN Enter PIN..................................................................................................72
3.2.29 AT+CPWD Change Password...................................................................................73
3.2.30 AT+CR Service Reporting Control ...........................................................................74
3.2.31 AT+CRC Set Cellular Result Codes for Incoming Call Indication ...........................74
3.2.32 AT+CREG Network Registration..............................................................................75
3.2.33 AT+CRLP Select Radio Link Protocol Parameters ...................................................77
3.2.34 AT+CRSM Restricted SIM Access ...........................................................................77
3.2.35 AT+CSQ Signal Quality Report ................................................................................78
3.2.36 AT+FCLASS FAX: Select, Read or Test Service Class ............................................79
3.2.37 AT+FMI FAX: Report Manufactured ID...................................................................80
3.2.38 AT+FMM FAX: Report Model ID ............................................................................80
3.2.39 AT+FMR FAX: Report Revision ID .........................................................................80
3.2.40 AT+VTD Tone Duration............................................................................................81
3.2.41 AT+VTS DTMF and Tone Generation ......................................................................81
3.2.42 AT+CMUX Multiplexer Control...............................................................................82
3.2.43 AT+CNUM Subscriber Number................................................................................84
3.2.44 AT+CPOL Preferred Operator List............................................................................85
3.2.45 AT+COPN Read Operator Names.............................................................................85
3.2.46 AT+CFUN Set Phone Functionality..........................................................................86
3.2.47 AT+CCLK Clock.......................................................................................................87
3.2.48 AT+CSIM Generic SIM Access ................................................................................87
3.2.49 AT+CALM Alert Sound Mode..................................................................................88
3.2.50 AT+CALS Alert Sound Select...................................................................................89
3.2.51 AT+CRSL Ringer Sound Level.................................................................................89
3.2.52 AT+CLVL Loud Speaker Volume Level ...................................................................90
3.2.53 AT+CMUT Mute Control..........................................................................................91
3.2.54 AT+CPUC Price Per Unit and Currency Table..........................................................92
3.2.55 AT+CCWE Call Meter Maximum Event ..................................................................92
3.2.56 AT+CBC Battery Charge...........................................................................................93
3.2.57 AT+CUSD Unstructured Supplementary Service Data.............................................94
3.2.58 AT+CSSN Supplementary Services Notification ......................................................95
4 AT Commands According to GSM07.05.....................................................................................97
4.1 Overview of AT Commands According to GSM07.05..........................................................97
4.2 Detailed Descriptions of AT Commands According to GSM07.05.......................................97
4.2.1 AT+CMGD Delete SMS Message...............................................................................97
4.2.2 AT+CMGF Select SMS Message Format ...................................................................98
4.2.3 AT+CMGL List SMS Messages from Preferred Store................................................99
4.2.4 AT+CMGR Read SMS Message ...............................................................................102
4.2.5 AT+CMGS Send SMS Message................................................................................105
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4.2.6 AT+CMGW Write SMS Message to Memory ..........................................................106
4.2.7 AT+CMSS Send SMS Message from Storage ..........................................................108
4.2.8 AT+CNMI New SMS Message Indications ..............................................................108
4.2.9 AT+CPMS Preferred SMS Message Storage ............................................................ 111
4.2.10 AT+CRES Restore SMS Settings............................................................................ 111
4.2.11 AT+CSAS Save SMS Settings ................................................................................ 112
4.2.12 AT+CSCA SMS Service Center Address ................................................................ 113
4.2.13 AT+CSCB Select Cell Broadcast SMS Messages................................................... 114
4.2.14 AT+CSDH Show SMS Text Mode Parameters ....................................................... 115
4.2.15 AT+CSMP Set SMS Text Mode Parameters ........................................................... 115
4.2.16 AT+CSMS Select Message Service......................................................................... 116
5 AT Commands for SIM Application Toolkit.............................................................................118
5.1 STK AT Command.............................................................................................................. 118
6 AT Commands Special for SIMCOM........................................................................................120
6.1 Overview.............................................................................................................................120
6.2 Detailed Descriptions of Commands...................................................................................121
6.2.1 AT+SIDET
Change the Side Tone Gain Level.......................................................121
6.2.2 AT+CPOWD Power Off ...........................................................................................122
6.2.3 AT+SPIC Times Remained to Input SIM PIN/PUK.................................................122
6.2.4 AT+CMIC Change the Microphone Gain Level.......................................................123
6.2.5 AT+CALA Set Alarm Time......................................................................................124
6.2.6 AT+CALD Delete Alarm..........................................................................................125
6.2.7 AT+CADC Read ADC .............................................................................................125
6.2.8 AT+CSNS Single Numbering Scheme .....................................................................125
6.2.9 AT+CDSCB Reset Cell Broadcast............................................................................126
6.2.10 AT+CMOD Configure Alternating Mode Calls .....................................................126
6.2.11 AT+CFGRI Indicate RI When Using URC ............................................................127
6.2.12 AT+CLTS Get Local Timestamp............................................................................127
6.2.13 AT+CEXTHS External Headset Jack Control ........................................................129
6.2.14 AT+CEXTBUT Headset Button Status Reporting .................................................130
6.2.15 AT+CSMINS SIM Inserted Status Reporting.........................................................131
6.2.16 AT+CLDTMF Local DTMF Tone Generation .......................................................131
6.2.17 AT+CDRIND CS Voice/Data Call Termination Indication ...................................132
6.2.18 AT+CSPN Get Service Provider Name from SIM ..................................................133
6.2.19 AT+CCVM Get and Set the Voice Mail Number on the SIM .................................133
6.2.20 AT+CBAND Get and Set Mobile Operation Band .................................................134
6.2.21 AT+CHF Configure Hands Free Operation.............................................................135
6.2.22 AT+CHFA Swap the Audio Channels .....................................................................135
6.2.23 AT+CSCLK Configure Slow Clock ........................................................................136
6.2.24 AT+CENG Switch On or Off Engineering Mode ...................................................137
6.2.25 AT+SCLASS0 Store Class 0 SMS to SIM When Received Class 0 SMS ..............139
6.2.26 AT+CCID Show ICCID ..........................................................................................139
6.2.27 AT+CMTE Set Critical Temperature Operating Mode or Query Temperature ......139
6.2.28 AT+CBTE Battery Temperature Query...................................................................140
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6.2.29 AT+CSDT Switch On or Off Detecting SIM Card.................................................140
6.2.30 AT+CMGDA Delete All SMS................................................................................141
6.2.31 AT+STTONE Play SIM Toolkit Tone....................................................................142
6.2.32 AT+SIMTONE Generate Specifically Tone...........................................................143
6.2.33 AT+CCPD Enable or Disable Alpha String............................................................143
6.2.34 AT+CGID Get SIM Card Group Identifier.............................................................144
6.2.35 AT+MORING Show State of Mobile Originated Call............................................144
6.2.36 AT+CMGHEX Enable or Disable Sending Non-ASCII Character SMS ...............145
6.2.37AT+AUTEST Audio Channel Loopback Test.........................................................146
6.2.38AT+CCODE Configure SMS Code Mode...............................................................146
6.2.39 AT+CIURC Enable or Disable Initial URC Presentation .......................................147
6.2.40 AT+CPSPWD Change PS Super Password ............................................................147
6.2.41 AT+EXUNSOL Enable or Disable Proprietary Unsolicited Indications .................148
6.2.42 AT+CGMSCLASS Change GPRS Multislot Class ................................................148
6.2.43 AT+CDEVICE View Current Flash Device Type ..................................................149
6.2.44 AT+CCALR Call Ready Query ..............................................................................149
6.2.45 AT+GSV Display Product Identification Information.............................................150
6.2.46 AT+SGPIO Control the GPIO .................................................................................150
6.2.47 AT+SPWM Generate the Pulse-Width-Modulation ................................................151
6.2.48 AT+ECHO Echo Cancellation Control ...................................................................152
6.2.49 AT+CAAS Control Auto Audio Switch ..................................................................153
6.2.50 AT+SVR Configure Voice Coding Type for Voice Calls.........................................154
6.2.51 AT+GSMBUSY Reject Incoming Call....................................................................155
7 AT Commands for GPRS Support.............................................................................................156
7.1 Overview of AT Commands for GPRS Support..................................................................156
7.2 Detailed Descriptions of AT Commands for GPRS Support...............................................156
7.2.1 AT+CGATT Attach or Detach from GPRS Service ..................................................156
7.2.2 AT+CGDCONT Define PDP Context .......................................................................157
7.2.3 AT+CGQMIN Quality of Service Profile (Minimum Acceptable) ...........................159
7.2.4 AT+CGQREQ Quality of Service Profile (Requested) .............................................160
7.2.5 AT+CGACT PDP Context Activate or Deactivate ....................................................162
7.2.6 AT+CGDATA Enter Data State .................................................................................162
7.2.7 AT+CGPADDR Show PDP Address .........................................................................163
7.2.8 AT+CGCLASS GPRS Mobile Station Class.............................................................164
7.2.9 AT+CGEREP Control Unsolicited GPRS Event Reporting ......................................165
7.2.10 AT+CGREG Network Registration Status ..............................................................166
7.2.11 AT+CGSMS Select Service for MO SMS Messages ..............................................167
8 AT Commands for TCPIP Application Toolkit .........................................................................169
8.1 Overview.............................................................................................................................169
8.2 Detailed Descriptions of Commands...................................................................................170
8.2.1 AT+CIPMUX Start Up Multi-IP Connection ............................................................170
8.2.2 AT+CIPSTART Start Up TCP or UDP Connection...................................................170
8.2.3 AT+CIPSEND Send Data Through TCP or UDP Connection...................................172
8.2.4 AT+CIPQSEND Select Data Transmitting Mode .....................................................174
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8.2.5 AT+CIPACK Query Previous Connection Data Transmitting State..........................175
8.2.6 AT+CIPCLOSE Close TCP or UDP Connection .....................................................176
8.2.7 AT+CIPSHUT Deactivate GPRS PDP Context ........................................................176
8.2.8 AT+CLPORT Set Local Port .....................................................................................177
8.2.9 AT+CSTT Start Task and Set APN, USER NAME, PASSWORD...........................177
8.2.10 AT+CIICR Bring Up Wireless Connection with GPRS or CSD .............................178
8.2.11 AT+CIFSR Get Local IP Address............................................................................179
8.2.12 AT+CIPSTATUS Query Current Connection Status ...............................................179
8.2.13 AT+CDNSCFG Configure Domain Name Server...................................................181
8.2.14 AT+CDNSGIP Query the IP Address of Given Domain Name...............................181
8.2.15 AT+CIPHEAD Add an IP Head at the Beginning of a Package Received..............182
8.2.16 AT+CIPATS Set Auto Sending Timer .....................................................................183
8.2.17 AT+CIPSPRT Set Prompt of ‘>’ When Module Sends Data...................................183
8.2.18 AT+CIPSERVER Configure Module as Server ......................................................184
8.2.19 AT+CIPCSGP Set CSD or GPRS for Connection Mode ........................................185
8.2.20 AT+CIPSRIP Show Remote IP Address and Port When Received Data ................186
8.2.21 AT+CIPDPDP Set Whether to Check State of GPRS Network Timing ..................187
8.2.22 AT+CIPMODE Select TCPIP Application Mode....................................................188
8.2.23AT+CIPCCFG Configure Transparent Transfer Mode ............................................188
8.2.24 AT+CIPSHOWTP Display Transfer Protocol in IP Head When Received Data.....189
8.2.25 AT+CIPUDPMODE UDP Extended Mode.............................................................190
8.2.26 AT+CIPRXGET Get Data from Network Manually ...............................................191
8.2.27 AT+CIPQRCLOSE Quick Remote Close ...............................................................192
8.2.28 AT+CIPSCONT Save TCPIP Application Context .................................................192
9 AT Commands for IP Application .............................................................................................194
9.1 Overview.............................................................................................................................194
9.2 Detailed Descriptions of Commands...................................................................................194
9.2.1 AT+SAPBR Bearer Settings for Applications Based on IP.......................................194
10 AT Commands for HTTP Application.....................................................................................196
10.1 Overview...........................................................................................................................196
10.2 Detailed Descriptions of Commands.................................................................................196
10.2.1 AT+HTTPINIT Initialize HTTP Service .................................................................196
10.2.2 AT+HTTPTERM Terminate HTTP Service ............................................................196
10.2.3 AT+HTTPPARA Set HTTP Parameters Value ........................................................197
10.2.4 AT+HTTPDATA Input HTTP Data .........................................................................198
10.2.5 AT+HTTPACTION HTTP Method Action .............................................................199
10.2.6 AT+HTTPREAD Read the HTTP Server Response................................................201
10.2.7 AT+HTTPSCONT Save HTTP Application Context ..............................................202
11 AT Commands for FTP Application........................................................................................203
11.1 Overview ...........................................................................................................................203
11.2 Detailed Descriptions of Commands.................................................................................203
11.2.1 AT+FTPPORT Set FTP Control Port.......................................................................203
11.2.2 AT+FTPMODE Set Active or Passive FTP Mode...................................................204
11.2.3 AT+FTPTYPE Set the Type of Data to Be Transferred...........................................205
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11.2.4 AT+FTPPUTOPT Set FTP Put Type .......................................................................205
11.2.5 AT+FTPCID Set FTP Bearer Profile Identifier .......................................................206
11.2.6 AT+FTPREST Set Resume Broken Download .......................................................206
11.2.7 AT+FTPSERV Set FTP Server Address ..................................................................207
11.2.8 AT+FTPUN Set FTP User Name ............................................................................208
11.2.9 AT+FTPPW Set FTP Password ...............................................................................208
11.2.10 AT+FTPGETNAME Set Download File Name ....................................................209
11.2.11 AT+FTPGETPATH Set Download File Path .........................................................209
11.2.12 AT+FTPPUTNAME Set Upload File Name .........................................................210
11.2.13 AT+FTPPUTPATH Set Upload File Path .............................................................. 211
11.2.14 AT+FTPGET Download File................................................................................. 211
11.2.15 AT+FTPPUT Set Upload File................................................................................212
11.2.16 AT+FTPSCONT Save FTP Application Context ..................................................213
12 Supported Unsolicited Result Codes........................................................................................215
12.1 Summary of CME ERROR Codes ....................................................................................215
12.2 Summary of CMS ERROR Codes ....................................................................................216
13 AT Commands Sample ............................................................................................................219
13.1 Profile Commands.............................................................................................................219
13.2 SIM Commands ................................................................................................................220
13.3 General Commands...........................................................................................................221
13.4 Call Control Commands....................................................................................................222
13.5 SIM Toolkit Commands ....................................................................................................224
13.6 Audio Commands..............................................................................................................224
13.7 SMS Commands ...............................................................................................................224
13.8 GPRS Commands .............................................................................................................226

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1 Introduction
1.1 Scope of the document
This document presents the AT Command Set for SIMCOM SIM900 series cellular engine.

1.2 Related documents

You can visit the SIMCom Website using the following link:
http://www.sim.com

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1.3 Conventions and abbreviations
In this document, the GSM engines are referred to as following term:
1) ME (Mobile Equipment);
2) MS (Mobile Station);
3) TA (Terminal Adapter);
4) DCE (Data Communication Equipment) or facsimile DCE (FAX modem, FAX board);
In application, controlling device controls the GSM engine by sending AT Command via its serial
interface. The controlling device at the other end of the serial line is referred to as following term:
1) TE (Terminal Equipment);
2) DTE (Data Terminal Equipment) or plainly "the application" which is running on an
embedded system;

1.4 AT Command syntax
The "AT" or "at" prefix must be set at the beginning of each Command line. To terminate a
Command line enter .
Commands are usually followed by a response that includes. ""
Throughout this document, only the responses are presented,  are omitted
intentionally.
The AT Command set implemented by SIM900 is a combination of GSM07.05, GSM07.07 and
ITU-T recommendation V.25ter and the AT commands developed by SIMCom.
Note: A HEX string such as "00 49 49 49 49 FF FF FF FF" will be sent out through serial
port at the baud rate of 115200 immediately after SIM900 is powered on. The string shall be
ignored since it is used for synchronization with PC tool. Only enter AT Command through
serial port after SIM900 is powered on and Unsolicited Result Code "RDY" is received from
serial port. If auto-bauding is enabled, the Unsolicited Result Codes "RDY" and so on are
not indicated when you start up the ME, and the "AT" prefix, not "at" prefix must be set at
the beginning of each command line.
All these AT commands can be split into three categories syntactically: "basic", "S parameter",
and "extended". These are as follows:
1.4.1 Basic syntax
These AT commands have the format of "AT", or "AT&", where ""is the
Command, and ""is/are the argument(s) for that Command. An example of this is "ATE",
which tells the DCE whether received characters should be echoed back to the DTE according to
the value of "". "" is optional and a default will be used if missing.

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1.4.2 S Parameter syntax
These AT commands have the format of "ATS=", where "" is the index of the S
register to set, and ""is the value to assign to it. "" is optional; if it is missing, then a
default value is assigned.
1.4.3 Extended Syntax
These commands can operate in several modes, as in the following table:

Table 1: Types of AT commands and responses
Test Command

AT+=?

The mobile equipment returns the list of parameters
and value ranges set with the corresponding Write
Command or by internal processes.

Read Command

AT+?

This command returns the currently set value of the
parameter or parameters.

Write Command

AT+=<…>

This command sets the user-definable parameter
values.

Execution Command

AT+

The execution command reads non-variable
parameters affected by internal processes in the GSM
engine.

1.4.4 Combining AT commands on the same Command line
You can enter several AT commands on the same line. In this case, you do not need to type the
"AT" or "at" prefix before every command. Instead, you only need type "AT" or "at" the
beginning of the command line. Please note to use a semicolon as the command delimiter after an
extended command, for example: ATE1&W&F+ICF?; +CFUN?; &W.
The Command line buffer can accept a maximum of 556 characters. If the characters entered
exceeded this number then none of the Command will executed and TA will return "ERROR".
1.4.5 Entering successive AT commands on separate lines
When you need to enter a series of AT commands on separate lines, please Note that you need to
wait the final response (for example OK, CME error, CMS error) of last AT Command you entered
before you enter the next AT Command.

1.5 Supported character sets
The SIM900 AT Command interface defaults to the IRA character set. The SIM900 supports the
following character sets:
•
•

GSM format
UCS2

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• HEX
• IRA
• PCCP
• PCDN
• 8859-1
The character set can be set and interrogated using the "AT+CSCS" Command (GSM 07.07).
The character set is defined in GSM specification 07.05.
The character set affects transmission and reception of SMS and SMS Cell Broadcast messages,
the entry and display of phone book entries text field and SIM Application Toolkit alpha strings.

1.6 Flow control
Flow control is very important for correct communication between the GSM engine and DTE. For
in the case such as a data or fax call, the sending device is transferring data faster than the
receiving side is ready to accept. When the receiving buffer reaches its capacity, the receiving
device should be capable to cause the sending device to pause until it catches up.
There are basically two approaches to achieve data flow control: software flow control and
hardware flow control. SIM900 support both two kinds of flow control.
In Multiplex mode, it is recommended to use the hardware flow control.
1.6.1 Software flow control (XON/XOFF flow control)
Software flow control sends different characters to stop (XOFF, decimal 19) and resume (XON,
decimal 17) data flow. It is quite useful in some applications that only use three wires on the serial
interface.
The default flow control approach of SIM900 is hardware flow control (RTS/CTS flow control), to
enable software flow control in the DTE interface and within GSM engine, type the following AT
Command:
AT+IFC=1, 1
This setting is stored volatile, for use after restart, AT+IFC=1, 1 should be stored to the user
profile with AT&W.
NOTE:
The AT commands listed in the table of AT&W chapter should be stored to user profile with
AT&W for use after restart. Most other AT commands in V.25, 07.05, 07.07, GPRS will store
parameters automatically and can be used after module restart.

Ensure that any communications software package (e.g. Hyper terminal) uses software flow
control.
NOTE:
Software Flow control should not be used for data calls where binary data will be transmitted or
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received (e.g. TCP/IP) as the DTE interface may interpret binary data as flow control characters.
1.6.2 Hardware flow control (RTS/CTS flow control)
Hardware flow control achieves the data flow control by controlling the RTS/CTS line. When the
data transfer should be suspended, the CTS line is set inactive until the transfer from the receiving
buffer has completed. When the receiving buffer is ok to receive more data, CTS goes active once
again.
To achieve hardware flow control, ensure that the RTS/CTS lines are present on your application
platform.

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2 AT Commands According to V.25TER
These AT Commands are designed according to the ITU-T (International Telecommunication
Union, Telecommunication sector) V.25ter document.

2.1 Overview of AT Commands According to V.25TER
Command

Description

A/

RE-ISSUES THE LAST COMMAND GIVEN

ATA

ANSWER AN INCOMING CALL

ATD

MOBILE ORIGINATED CALL TO DIAL A NUMBER

ATD>

ORIGINATE CALL TO PHONE NUMBER IN CURRENT MEMORY

ATD>

ORIGINATE CALL TO PHONE NUMBER IN MEMORY WHICH
CORRESPONDS TO FIELD 

ATDL

REDIAL LAST TELEPHONE NUMBER USED

ATE

SET COMMAND ECHO MODE

ATH

DISCONNECT EXISTING CONNECTION

ATI

DISPLAY PRODUCT IDENTIFICATION INFORMATION

ATL

SET MONITOR SPEAKER LOUDNESS

ATM

SET MONITOR SPEAKER MODE

+++

SWITCH FROM DATA MODE OR PPP ONLINE MODE TO
COMMAND MODE

ATO

SWITCH FROM COMMAND MODE TO DATA MODE

ATP

SELECT PULSE DIALLING

ATQ

SET RESULT CODE PRESENTATION MODE

ATS0

SET NUMBER OF RINGS
ANSWERING THE CALL

ATS3

SET COMMAND LINE TERMINATION CHARACTER

ATS4

SET RESPONSE FORMATTING CHARACTER

ATS5

SET COMMAND LINE EDITING CHARACTER

ATS6

PAUSE BEFORE BLIND DIALLING

ATS7

SET NUMBER OF SECONDS TO WAIT FOR CONNECTION
COMPLETION

ATS8

SET NUMBER OF SECONDS TO WAIT FOR COMMA DIAL
MODIFIER ENCOUNTERED IN DIAL STRING OF D COMMAND

ATS10

SET DISCONNECT DELAY AFTER INDICATING THE ABSENCE OF
DATA CARRIER

ATT

SELECT TONE DIALING

ATV

TA RESPONSE FORMAT

ATX

SET CONNECT RESULT CODE FORMAT AND MONITOR CALL

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PROGRESS
ATZ

RESET DEFAULT CONFIGURATION

AT&C

SET DCD FUNCTION MODE

AT&D

SET DTR FUNCTION MODE

AT&F

FACTORY DEFINED CONFIGURATION

AT&V

DISPLAY CURRENT CONFIGURATION

AT&W

STORE ACTIVE PROFILE

AT+GCAP

REQUEST COMPLETE TA CAPABILITIES LIST

AT+GMI

REQUEST MANUFACTURER IDENTIFICATION

AT+GMM

REQUEST TA MODEL IDENTIFICATION

AT+GMR

REQUEST TA REVISION
RELEASE

AT+GOI

REQUEST GLOBAL OBJECT IDENTIFICATION

AT+GSN

REQUEST TA SERIAL NUMBER IDENTIFICATION (IMEI)

AT+ICF

SET TE-TA CONTROL CHARACTER FRAMING

AT+IFC

SET TE-TA LOCAL DATA FLOW CONTROL

AT+IPR

SET TE-TA FIXED LOCAL RATE

AT+HVOIC

DISCONNECT VOICE CALL ONLY

IDENTIFICATION

OF

SOFTWARE

2.2 Detailed Description of AT Commands According to V.25TER
2.2.1 A/
A/

Re-issues the Last Command Given

Re-issues the Last Command Given

Execution
Command
A/

Response
Re-issues the previous Command

Reference
V.25ter

Note

2.2.2 ATA ANSWER AN INCOMING CALL
ATA ANSWER AN INCOMING CALL

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Execution
Command
ATA

Response
TA sends off-hook to the remote station.
Note1: Any additional commands on the same Command line are ignored.
Note2: This Command may be aborted generally by receiving a character
during execution. The aborting is not possible during some states of
connection establishment such as handshaking.
Response in case of data call, if successfully connected
CONNECT TA switches to data mode.
Note:  output only if ATX parameter setting with the
>0
When TA returns to Command mode after call release
OK
Response in case of voice call, if successfully connected
OK
Response if no connection
NO CARRIER

Reference
V.25ter
2.2.3 ATD
ATD

Note
See also ATX
Mobile Originated Call to Dial A Number

Mobile Originated Call to Dial A Number

Execution
Command
ATD[ TA switches to data mode.
Note:  output only if ATX parameter setting with the
 >0
When TA returns to Command mode after call release
OK
If connection successful and voice call
OK
Parameters

String of dialing digits and optionally V.25ter modifiers dialing
digits:
0-9, * , #, +, A, B, C
Following V.25ter modifiers are ignored:
,(comma), T, P, !, W, @
Emergency call:

Standardized emergency number 112 (no SIM needed)

String of GSM modifiers:
I
Actives CLIR (Disables presentation of own number
to called party)
i
Deactivates CLIR (Enable presentation of own number
to called party)
G
Activates Closed User Group invocation for this call
only
g
Deactivates Closed User Group invocation for this call
only
<;>
Only required to set up voice call , return to Command state
Reference
V.25ter

Note
z Parameter "I" and "i" only if no *# code is within the dial string
z  is default for last number that can be dialed by ATDL
z *# codes sent with ATD are treated as voice calls. Therefore, the
Command must be terminated with a semicolon ";"
z See ATX Command for setting result code and call monitoring
parameters.
Responses returned after dialing with ATD
z For voice call two different responses mode can be determined. TA
returns "OK" immediately either after dialing was completed or after
the call is established. The setting is controlled by AT+COLP. Factory
default is AT+COLP=0, this cause the TA returns "OK" immediately

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after dialing was completed, otherwise TA will returns "OK",
"BUSY", "NO DIAL TONE", "NO CARRIER".
Using ATD during an active voice call:
z When a user originates a second voice call while there is already an
active voice call, the first call will be automatically put on hold.
z The current states of all calls can be easily checked at any time by
using the AT+CLCC Command.

2.2.4 ATD>
ATD>

Originate Call to Phone Number in Current Memory

Originate Call to Phone Number in Current Memory

Execution
Command
ATD>[
][ ][;]

Response
This Command can be used to dial a phone number from current phonebook
memory.
Note: This Command may be aborted generally by receiving an ATH
Command or a character during execution. The aborting is not possible
during some states of connection establishment such as handshaking.
If error is related to ME functionality
+CME ERROR: 
If no dial tone and (parameter setting ATX2 or ATX4)
NO DIALTONE
If busy and (parameter setting ATX3 or ATX4)
BUSY
If a connection cannot be established
NO CARRIER
If the remote station does not answer
NO ANSWER
If connection successful and non-voice call.
CONNECT TA switches to data mode.
Note:  output only if ATX parameter setting with the
 >0
When TA returns to Command mode after call release
OK
If successfully connected and voice call

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OK
Parameters




Integer type memory location should be in the range of
locations available in the memory used
String of GSM modifiers:
I

i

Override the CLIR supplementary service subscription
default value for this call
Invocation (restrict CLI presentation)
Override the CLIR supplementary service subscription
default value for this call
Suppression (allow CLI presentation)


Control the CUG supplementary service information
for this call
CUG Not supported
g
Control the CUG supplementary service information
for this call
CUG Not supported
Only required to set up voice call , return to Command state
G

<;>

Reference
V.25ter

Note
z Parameter "I" and "i" only if no *# code is within the dial string
z *# codes sent with ATD are treated as voice calls. Therefore, the
Command must be terminated with a semicolon ";"
z See ATX Command for setting result code and call monitoring
parameters.

2.2.5 ATD>

ATD>


Originate Call to Phone Number in Memory Which Corresponds to Field

Originate Call to Phone Number in Memory Which Corresponds to Field

Execution
Command
ATD>[][][;]

Response
This Command make the TA attempts to set up an outgoing call to stored
number.
All available memories are searched for the entry .
Note: This Command may be aborted generally by receiving an ATH
Command or a character during execution. The aborting is not possible
during some states of connection establishment such as handshaking.
If error is related to ME functionality
+CME ERROR: 
If no dial tone and (parameter setting ATX2 or ATX4)

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NO DIALTONE
If busy and (parameter setting ATX3 or ATX4)
BUSY
If a connection cannot be established
NO CARRIER
If the remote station does not answer
NO ANSWER
If connection successful and non-voice call.
CONNECT TA switches to data mode.
Note:  output only if ATX parameter setting with the
 >0
When TA returns to Command mode after call release
OK
If successfully connected and voice call
OK
Parameters




<;>
Reference
V.25ter

String type (string should be included in quotation marks)
value ("x"), which should equal to an alphanumeric field in
at least one phone book entry in the searched memories. str
formatted as current TE character set specified by +CSCS.
String of GSM modifiers:
I
Actives CLIR (Disables presentation of own number
to called party)
i Deactivates CLIR (Enable presentation of own number
to called party)
G Activates Closed User Group invocation for this call
only
g
Deactivates Closed User Group invocation for this call
only
only required to set up voice call , return to Command state

Note
z Parameter "I" and "i" only if no *# code is within the dial string
z *# codes sent with ATD are treated as voice calls. Therefore, the
Command must be terminated with a semicolon ";"
z See ATX Command for setting result code and call monitoring
parameters.

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2.2.6 ATDL Redial Last Telephone Number Used
ATDL Redial Last Telephone Number Used
Execution
Command
ATDL

Response
This Command redials the last voice and data call number used.
Note: This Command may be aborted generally by receiving an ATH
Command or a character during execution. The aborting is not possible
during some states of connection establishment such as handshaking.
If error is related to ME functionality
+CME ERROR: 
If no dial tone and (parameter setting ATX2 or ATX4)
NO DIALTONE
If busy and (parameter setting ATX3 or ATX4)
BUSY
If a connection cannot be established
NO CARRIER
If the remote station does not answer
NO ANSWER
If connection successful and non-voice call.
CONNECT TA switches to data mode.
Note:  output only if ATX parameter setting with the
 >0
When TA returns to Command mode after call release
OK
If successfully connected and voice call
OK

Reference
V.25ter

2.2.7 ATE
ATE

Note
z See ATX Command for setting result code and call monitoring
parameters.
z Return the numbers and symbols which ATD supports if there is no
last dialing context.
Set Command Echo Mode

Set Command Echo Mode

Execution

Response

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Command
ATE

This setting determines whether or not the TA echoes characters received
from TE during Command state.
OK
Parameter


Reference
V.25ter
2.2.8 ATH
ATH

0 Echo mode off
1 Echo mode on

Note

Disconnect Existing Connection

Disconnect Existing Connection

Execution
Command
ATH[n]

Response
Disconnect existing call by local TE from Command line and terminate call
OK
Note: OK is issued after circuit 109(DCD) is turned off, if it was previously
on.
Parameter

0 Disconnect ALL calls on the channel the command is
requested. All active or waiting calls, CS data calls, GPRS call
of the channel will be disconnected.
1 Disconnect all calls on ALL connected channels. All active or
waiting calls, CSD calls, GPRS call will be disconnected.
(clean up of all calls of the ME)
2 Disconnect all connected CS data call only on the channel
the command is requested. (speech calls (active or waiting)
or GPRS calls are not disconnected)
3 Disconnect all connected GPRS calls only on the channel
the command is requested (speech calls (active or waiting)
or CS data calls are not disconnected.
4 Disconnect all CS calls (either speech or data) but does not
disconnect waiting call (either speech or data) on the
channel the command is requested.
5 Disconnect waiting call (either speech or data) but does not
disconnect other active calls (either CS speech, CS data or
GPRS) on the channel the command is requested.
(rejection of incoming call)

Reference
V.25ter

Note

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2.2.9 ATI
ATI

Display Product Identification Information

Display Product Identification Information

Execution
Command
ATI

Response
TA issues product information text
Example:
SIM900 R11.0
OK

Reference
V.25ter

Note

2.2.10 ATL Set Monitor speaker loudness
ATL Set Monitor speaker loudness
Execution
Command
ATL
Reference
V.25ter

Response
OK
Parameter


0..9

volume

Note
No effect in GSM

2.2.11 ATM Set Monitor Speaker Mode
ATM

Set Monitor Speaker Mode

Execution
Command
ATM
Reference
V.25ter

Response
OK
Parameter


0..9

mode

Note
No effect in GSM

2.2.12 +++ Switch from Data Mode or PPP Online Mode to Command Mode
+++

Switch from Data Mode or PPP Online Mode to Command Mode

Execution
Command
+++

Response
The +++ character sequence causes the TA to cancel the data flow over the
AT interface and switch to Command mode. This allows you to enter AT
Command while maintaining the data connection to the remote server.
OK
To prevent the +++ escape sequence from being misinterpreted as data, it
should comply to following sequence:

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1.
2.
3.
4.

No characters entered for T1 time (1 second)
"+++" characters entered with no characters in between (0.5 second)
No characters entered for T1 timer (0.5 second)
Switch to Command mode, otherwise go to step 1.

Parameter
Reference
V.25ter

Note
To return from Command mode back to data mode: Enter ATO.

2.2.13 ATO Switch from Command Mode to Data Mode
ATO

Switch from Command Mode to Data Mode

Execution
Command
ATO[n]

Response
TA resumes the connection and switches back from Command mode to data
mode.
CONNECT
If connection is not successfully resumed
NO CARRIER
else
TA returns to data mode from Command mode CONNECT  Note:
 only if parameter setting ATX>0
Parameter

0

Reference
V.25ter

Switch from Command mode to data mode.

Note

2.2.14 ATP Select Pulse Dialling
ATP Select Pulse Dialling
Execution
Command
ATP

Response
OK

Reference
V.25ter

Note
No effect in GSM

2.2.15 ATQ Set Result Code Presentation Mode
ATQ

Set Result Code Presentation Mode

Execution
Command
ATQ

Response
This parameter setting determines whether or not the TA transmits any result
code to the TE. Information text transmitted in response is not affected by
this setting.

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If =0:
OK
If =1:
(none)
Parameter

0 TA transmits result code
1 Result codes are suppressed and not transmitted
Reference
V.25ter

Note

2.2.16 ATS0 Set Number of Rings before Automatically Answering the Call
ATS0

Set Number of Rings before Automatically Answering the Call

Read Command
ATS0?

Response

OK
Parameter
See Write Command

Write Command
ATS0=

Response
This parameter setting determines the number of rings before auto-answer.
OK
ERROR
Parameter

0
Automatic answering is disable.
1-255 Number of rings the modem will wait for before answering
the phone if a ring is detected.

Reference
V.25ter

Note
If  is set too high, the calling party may hang up before the call can be
answered automatically.

2.2.17 ATS3 Set Command Line Termination Character
ATS3

Set Command Line Termination Character

Read Command
ATS3?

Response

OK
Parameter
See Write Command

Write Command
ATS3=

Response
This parameter setting determines the character recognized by TA to

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terminate an incoming Command line. The TA also returns this character in
output.
OK
ERROR
Parameter

13 Command line termination character
Reference
V.25ter
2.2.18 ATS4
ATS4

Note
Default 13 = CR. It only supports default value.
Set Response Formatting Character

Set Response Formatting Character

Read Command
ATS4?

Response

OK
Parameter
See Write Command

Write Command
ATS4=

Response
This parameter setting determines the character generated by the TA for
result code and information text.
OK
ERROR
Parameter

10 Response formatting character

Reference
V.25ter
2.2.19 ATS5
ATS5

Note
Default 10 = LF. It only supports default value.
Set Command Line Editing Character

Set Command Line Editing Character

Read Command
ATS5?

Response

OK
Parameter
See Write Command

Write Command
ATS5=

Response
This parameter setting determines the character recognized by TA as a
request to delete from the Command line the immediately preceding

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character.
OK
ERROR
Parameter

0-8-127
Reference
V.25ter
2.2.20 ATS6
ATS6

Response formatting character

Note
Default 8 = Backspace.
Pause Before Blind Dialling

Pause Before Blind Dialling

Read Command
ATS6?

Response
ERROR

Write Command
ATS6=

Response
OK
ERROR
Parameter

0..999

Reference
V.25ter

Time

Note
No effect in GSM

2.2.21 ATS7 Set Number of Seconds to Wait for Connection Completion
ATS7

Set Number of Seconds to Wait for Connection Completion

Read Command
ATS7?

Response

OK
Parameter
See Write Command

Write Command
ATS7=

Response
This parameter setting determines the amount of time to wait for the
connection completion in case of answering or originating a call.
OK
ERROR
Parameter

1-60-255

Reference

Number of seconds to wait for connection completion

Note

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z

V.25ter

z
z
z

If called party has specified a high value for ATS0=, call setup may
fail.
The correlation between ATS7 and ATS0 is important
Example: Call may fail if ATS7=30 and ATS0=20.
ATS7 is only applicable to data call.

2.2.22 ATS8 Set Number of Seconds to Wait for Comma Dial Modifier Encountered in Dial
String of D Command
ATS8 Set Number of Seconds to Wait for Comma Dial Modifier Encountered in Dial
String of D Command
Read Command
ATS8?

Response

OK
Parameter
See Write Command

Write Command
ATS8=

Response
OK
ERROR
Parameter

0-255 The value of this register determines how long the modem
should pause when it sees a comma in the dialing string.

Reference
V.25ter
2.2.23 ATS10
ATS10

Note
No effect in GSM
Set Disconnect Delay after Indicating the Absence of Data Carrier

Set Disconnect Delay after Indicating the Absence of Data Carrier

Read Command
ATS10?

Response

OK
Parameter
See Write Command

Write Command
ATS10=

Response
This parameter setting determines the amount of time that the TA will
remain connected in absence of data carrier. If the data carrier is once more
detected before disconnecting, the TA remains connected.
OK
ERROR
Parameter

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Reference
V.25ter

1-15-254

Number of tenths seconds of delay

Note

2.2.24 ATT Select Tone Dialing
ATT Select Tone Dialing
Execution
Command
ATT

Response
OK

Reference
V.25ter

Note
No effect in GSM

2.2.25 ATV

TA Response Format

ATV TA Response Format
Execution
Command
ATV

Response
This parameter setting determines the contents of the header and trailer
transmitted with result codes and information responses.
When =0
0
When =1
OK
Parameter


Information response: 
Short result code format: 
1 Information response: 
Long result code format: 

The result codes, their numeric equivalents and brief descriptions of the use
of each are listed in the following table.
Reference
V.25ter

0

Note

ATV1

ATV0

Description

OK

0

Acknowledges execution of a Command

CONNECT

1

A connection has been established; the DCE is moving
from Command state to online data state

RING

2

The DCE has detected an incoming call signal from
network

NO CARRIER

3

The connection has been terminated or the attempt to
establish a connection failed

ERROR

4

Command not recognized, Command line maximum

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length exceeded, parameter value invalid, or other
problem with processing the Command line
NO DIALTONE

6

No dial tone detected

BUSY

7

Engaged (busy) signal detected

NO ANSWER

8

"@" (Wait for Quiet Answer) dial modifier was used,
but remote ringing followed by five seconds of silence
was not detected before expiration of the connection
timer (S7)

PROCEEDING

9

An AT command is being processed

CONNECT


Manufacturerspecific

Same
as
CONNECT,
but
includes
manufacturer-specific text that may specify DTE speed,
line speed, error control, data compression, or other
status

2.2.26 ATX
ATX

Set CONNECT Result Code Format and Monitor Call Progress

Set CONNECT Result Code Format and Monitor Call Progress

Execution
Command
ATX

Response
This parameter setting determines whether or not the TA detected the
presence of dial tone and busy signal and whether or not TA transmits
particular result codes.
OK
ERROR
Parameter


0
1
2
3
4

Reference
V.25ter
2.2.27 ATZ

CONNECT result code only returned, dial tone and busy
detection are both disabled.
CONNECT result code only returned, dial tone and
busy detection are both disabled.
CONNECT result code returned, dial tone
detection is enabled, busy detection is disabled.
CONNECT result code returned, dial tone
detection is disabled, busy detection is enabled.
CONNECT result code returned, dial tone and
busy detection are both enabled.

Note

Reset Default Configuration

ATZ Reset Default Configuration
Execution
Command
ATZ[]

Response
TA sets all current parameters to the user defined profile.
OK

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ERROR
Parameter

Reference
V.25ter

0 Restore profile 0
1 Restore profile 1

Note

Parameter impacted by Z command:
Command

Parameter name

Default value

ATE



0x01

ATQ



0x00

ATV



0x01

ATX



0x04

AT&C



0x01

AT&D



0x01

AT+IFC



0x00

AT+IFC



0x00

AT+FCLASS



0x00

ATS0



0x00

ATS3



0x00

ATS4



0x0D

ATS5



0x0A

ATS7