AT Command Set

Definition of AT Command Set

The AT Command Set, also known as the Hayes Command Set, is a collection of text-based commands used to control modems, mostly dial-up and wireless. The commands, which often start with the prefix “AT” (short for “Attention”), allow users to configure and control modem settings, establish internet connections, and perform other operations. This command set has been widely adopted and continues to be used in various modem-related applications and devices.


The phonetics of the keyword “AT Command Set” can be represented using the International Phonetic Alphabet (IPA) as: /ˈeɪ ˈti kəˈmænd ˈsɛt/

Key Takeaways

  1. AT Command Set is a set of short text-based commands that control modems and other communication devices, enabling communication and configuration between the devices and software programs.
  2. Originally designed for Hayes modems in the 1980s, AT Command Set has since been adopted as a standard for numerous communication devices like mobile phones, GPS modules, and IoT devices.
  3. AT commands are easy to use and can be sent through various interfaces, such as UART, USB, or TCP/IP, making them a flexible choice for establishing connections and managing communication devices.

Importance of AT Command Set

The AT Command Set is essential in the technology realm because it serves as a widely-adopted, standardized protocol for controlling modems and facilitating communication between computers or other devices through serial interfaces.

This command set enables users to establish and manipulate connections, access various modem functionalities, and exchange data, ensuring efficient and consistent performance across different platforms.

In addition to providing a simple and user-friendly way of interaction with modems, the AT command set’s broad compatibility also encourages the continued development and innovation in communication technologies, ultimately benefitting both consumers and manufacturers alike.


The AT Command Set, also known as the Hayes Command Set, serves a crucial role in telecommunications as a standardized interface for controlling modems and other communication devices. Originally developed in the early 1980s for Hayes Smartmodems, the AT Command Set has become an integral component in the management of various telecommunication services.

Its purpose lies in allowing users and software applications to execute commands, configure settings, and perform diagnostics, thus enabling streamlined and efficient communication between devices. The command set has evolved over time, incorporating new extensions and features to support a wide range of modems, including GSM, GPRS, and Bluetooth-enabled devices.

One of the primary uses of the AT Command Set involves establishing a connection between two devices. Through the use of easily recognizable instructions, users can manipulate data flow, speed, and connection parameters, as well as initiate and terminate a connection.

The AT Command Set is also vital in sending and receiving text messages, handling phone calls, and determining signal strength and network status in the realm of wireless communication devices. Ultimately, the AT Command Set enables a diverse set of communication devices to share a common language to control, monitor, and troubleshoot complex networks in a user-friendly manner.

Examples of AT Command Set

AT Command Set (short for Attention Command Set) is a collection of text-based instructions used to communicate with modems and other communication devices. These instructions, typically preceded by “AT” (short for “attention”), enable control, configuration, and status querying of devices. Here are three real-world examples of AT Command Set technology in use:

Mobile Phones and Wireless Modems: Mobile phones and wireless modems utilize AT commands to register onto cellular networks, establish a data connection, send/receive SMS, and control various functionality. For example, an embedded system using a GSM module could use an AT command like AT+CMGS to send an SMS or AT+CGATT=1 to attach to a GPRS service.

Bluetooth Modules: Devices such as the HC-05 Bluetooth module use AT commands to configure the device’s operating mode, baud rate, pairing settings, and other parameters. For example, AT+NAME can be used to set a custom name for the Bluetooth device, making it easier to identify.

Industrial IoT Applications: In industrial automation and IoT applications, AT commands can be used to configure and control various communication equipment, such as routers and IoT gateways. This allows the devices to connect to remote servers or cloud platforms for data transfer, remote monitoring, and control. For example, an IoT gateway might use an AT command like AT+CIPOPEN to establish a TCP connection to a remote server.AT Command Set plays a crucial role in the communication and configuration of various devices in these real-world applications and many others.

AT Command Set FAQ

1. What is the AT Command Set?

The AT Command Set, also known as Hayes command set, is a collection of text-based commands used to control modems. The commands are sent as ASCII characters and start with the prefix “AT” followed by various characters to specify the operation.

2. Why is it called AT Command Set?

The name “AT” comes from the abbreviation for “Attention,” which is the prefix used for all commands in the set. The modem interprets any command string starting with “AT” as a command and processes the subsequent characters accordingly.

3. How do I use AT commands with my modem?

In most cases, AT commands can be sent to the modem using a terminal emulator program or a custom script. You’ll need to establish a serial connection with the modem and then send the appropriate command strings preceded by the “AT” prefix.

4. Can AT commands control GSM/GPRS devices?

Yes, AT commands are commonly used to control GSM/GPRS devices, such as cellular modems and mobile phones. There is a specific set of AT commands, called GSM AT command set, which allows various operations, like making calls, sending SMS, and managing network connections.

5. How do I find the list of supported AT commands for my modem?

The list of supported AT commands can usually be found in the modem’s documentation, such as the user manual or a dedicated AT command set reference guide provided by the manufacturer. Additionally, some modems support the “AT+CLAC” command, which can be used to retrieve the list of supported commands and their descriptions.

Related Technology Terms

  • Hayes Command Set
  • Modem Control Commands
  • Serial Communication
  • Data Terminal Equipment (DTE)
  • Data Circuit-terminating Equipment (DCE)

Sources for More Information

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