Description of useful AT commands

12.07.2009 21:14

Please look at the initial page - how to start with if you want to get thorough information.


The communication with the GSM Module is based on AT commands. It is possible to set or read a lot of different parameters using this communication protocol.

The following description explains important and useful AT commands for communication with GSM Module. All commands are described further in the AT Commands Reference Guide from Telit.

Note: GSM Module GE863-QUAD used in the GSM Playground is equipped by the chipset version V3 so all the AT commands classified on #SELINT=0 and #SELINT=1 are supported.

It is possible to use a simple serial port terminal for receiving and sending of AT commands. You can use for example Termite. Remember to adjust the Switch for Serial communication located on the PCB to ON position to be able to communicate directly with the GSM module from PC.

The best way how to learn and understand following AT commands is to try them...

Press the ON/OFF Button on the GSM Playground for at least 1 second and set up the serial port terminal according the following picture. Port number might be different of course. 

Then if you type a command AT you will get OK, this means that the communication with the module is working. Let´s try the following AT commands now!


AUDIO (settings for usage of Mike and Speaker)

AT#CAP=1…change audio path to handsfree external mike and speaker („HF lines“)

AT#SHFEC=1…enables echo canceller for handsfree mode

AT#SRP=1 or 3…select ringer path for handsfree (1) or buzzer (3)

In case you select the buzzer then you need to allow to use GPIO7 as a buzzer output using this command: AT#GPIO=7,0,2

In case you select handsfree then you need to allow to use GPIO5 as a control of audio amplifier using this command: AT#GPIO=5,0,2. It means that the audio amplifier is only active in case it is needed otherwise it is in standby mode. There is also the possibility to adjust it so that the amplifier is still ON using AT#GPIO=5,1,1. This adjustment can be interesting for the testing purpose especially.

AT+CRSL=1 to 4...selects ringer sound level:

  • 0 - OFF      
  • 1 - low
  • 2 – middle
  • 3 - high
  • 4 – progressive

AT+CLVL=0 to 14…setting of speaker volume from 0 (min) to 14 (max)

AT+CMUT=0 or 1…mike mute control, 0 – mike is active, 1 – mike muted

AT#SRS=n,time…select ringer sound:

  • n – ringing tone number (0 to 32)
  • time – ringing tone playing time in seconds (1 to 60), 0 – the tone is adjusted only and it doesn’t play

AT#HFMICG=0 to 7… setting of microphone gain, 0 – minimum gain, 7 – maximum gain.

AT#CODEC=1…sets the Audio Codec to FR (Full Rate). This adjustment is important for the right decoding of DTMF signal.


User LED and User Button

These parts can be used as a simple output and input in your application or just for software development purpose.

User LED

AT#GPIO=8,1,1…LED lights up

AT#GPIO=8,0,1…LED switches off

User Button

AT#GPIO=9,0,0…set the GPIO9 as an input

AT#GPIO=9,2…read the status of use button

  • #GPIO: 0,1 – user button released
  • #GPIO: 0,0 – user button pushed


Temperature Sensor

The measurement of temperature is solved by the temperature sensor placed on the PCB (from the bottom side). This sensor has a calibrated linear scale factor +10mV/°C rated for full -25°C to +85°C range. The LM61 is calibrated to provide s accuracies of ±2.0°C at room temperature and ±3°C over the full −25°C to +85°C temperature range.

The voltage coming from the temperature sensor is measured by the GSM Module. Use the following command to read the analog value from the Module:


The Module will answer with the value in milivolts

The temperature can be counted according the following formula:




#ADC: 885


The temperature is (885 – 600)/10 = 28,5°C


User Connector

This connector can be used as a way to control or sense another circuits because it contains 4 general purpose inputs / outputs. It is intended for expanding of the GSM Playground based application. It can be used for e.g. sensing of inputs, switching of outputs or relays.

Power Outputs

The external application can be supplied directly from the User Connector using the following power outputs:

  • 5V / max approx. 200mA (the same voltage like for Arduino PCB)
  • 3,9V / max approx. 200mA (The same voltage as for the GSM Module)
  • VAUX1 (2,85V) / max 100mA (The output is active when the Module is ON and goes OFF when the Module is shut down)

AT#VAUX=1,0 or 1 or 2…disables (0) or enables (1) the VAUX1 voltage output, option (2) can be used for reading of the voltage output status.

General Purpose Inputs / Outputs (GPIO10-GPIO13)


Signal Function Type I/O Current Default State ON_OFF State

State during Reset

GPIO10 I / O CMOS 2,8V 1uA / 1mA INPUT LOW    
GPIO11 I / O CMOS 2,8V 1uA / 1mA INPUT HIGH HIGH 4,7k Pull Up
GPIO12 I / O CMOS 2,8V 1uA / 1mA INPUT HIGH HIGH 47k Pull Up
GPIO13 I / O CMOS 2,8V 1uA / 1mA INPUT LOW    


GPIO10 as an output

AT#GPIO=10,1,1…output pin set to 1 (HIGH)   

AT#GPIO=10,0,1… output pin cleared to 0 (LOW)

AT#GPIO=10,2…reads the value on the output

#GPIO: 1,1 – output pin set to 1 (HIGH)

#GPIO: 1,0 – output pin cleared to 0 (LOW)


GPIO10 as an input

AT#GPIO=10,0,0…set the pin direction to input

AT#GPIO=10,2…reads the value on the input   

#GPIO: 0,1 – input pin set to 1 (HIGH)

#GPIO: 0,0 – input pin set to 0 (LOW)


The controlling and reading of remaining pins GPIO11 to GPIO13 can be derived from described.



ATE0 or 1…echo ON (1) or OFF (0)

There is a requirement to switch ECHO OFF so that the GSM Module doesn’t disturb the communication between the PC and Arduino board during programming.


AT&F…Execution command sets the configuration parameters to default values specified by manufacturer; it takes in consideration hardware configuration switches and other manufacturer-defined criteria.

  • 0 - just the factory profile base section parameters are considered.
  • 1 - either the factory profile base section and the extended section are considered (full factory profile).

Note: if parameter is omitted, the command has the same behaviour as AT&F0


ATZ…Execution command loads the base section of the specified user profile and the extended section of the default factory profile.

  • 0, 1 - user profile number

Note: Any call in progress will be terminated. If parameter is omitted, the command has the same behaviour as ATZ0.


AT&W…Execution command stores on profile the complete configuration of the device.

  • 0, 1 - user profile number

Note: if parameter is omitted, the command has the same behavior of AT&W0.


ATDxxxxx;...Execution command starts a call to the phone number given as xxxxx.

If “;” is present at the end a voice call is performed.


ATA...Execution command is used to answer to an incoming call if automatic answer is disabled.


ATH...Execution command is used to close the current conversation (voice, data or fax). 


ATS0=0 or 1 to 255...sets the number of rings required before device automatically answers an incoming call

  • 0 - Auto answer is disabled
  • 1 to 255 is a number of rings required before automatic answer

Example: ATS0=1 answers an incoming call after the first ring


AT#BND=0, 1, 2 or 3...Select GSM Band

  • 0 - GSM 900MHz + DCS 1800MHz
  • 1 - GSM 900MHz + PCS 1900MHz
  • 2 - GMS 850MHz + DCS 1800MHz
  • 3 - GMS 850MHz + PCS 1900MHz


AT+COPS?...You get the mobile network operator name


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