As a part of my mobile phone project, I noticed some interesting AT Commands used to communicate with GSM modules.
These commands are the “language” that allows a microcontroller or PC to control the modem — managing calls, SMS, network, and hardware functions in detail.
Here’s a concise summary of commonly used GSM AT commands, grouped by function 👇
⚙️ Basic Connection & Testing
AT – Test connection between module and host
ATI – Display module identification
ATZ – Reset module
AT+CGMM – Get model identification
AT+GMR – Get firmware version
📞 Call Control
ATA – Answer incoming call
ATD – Dial a number (e.g., ATD+123456789;)
ATH – Hang up call
ATL – Speaker loudness
ATM – Speaker mode
ATP – Set pulse dial
ATT – Set tone dial
💬 SMS & Messaging
AT+CMGF – Set SMS mode (text or PDU)
AT+CMGS – Send SMS
AT+CMGR – Read SMS
AT+CMGL – List all messages
AT+CMGD – Delete SMS
AT+CSCA – SMS service center address
AT+CNMI – New SMS indication
📇 Phonebook Operations
AT+CPBS – Select phonebook memory
AT+CPBR – Read entries
AT+CPBW – Write new entry
AT+CPBF – Find entries
📡 Device & Network Info
AT+CGSN – Show IMEI
AT+COPS – Select network operator
AT+CREG – Registration status
AT+CBC – Battery charge info
AT+CSQ – Signal strength
🧠 Other Essential Commands
AT&W – Save configuration
AT&F – Restore factory settings
A/ – Repeat last command
AT+GCAP – List device capabilities
📘 Each GSM module (SIM800, SIM900, Quectel, etc.) may include additional vendor-specific AT commands. For full command sets, always refer to your module’s official AT Command Manual.
💡 Tip: Mastering these commands helps build reliable communication systems — from IoT devices to embedded projects.