Sending and Receiving SMS Messages with Quectel 4G Raspberry pi Hat
Introduction
In rural and remote areas, where 4G coverage is sparse or unavailable, SMS communication through 2G networks becomes a vital tool for ensuring uninterrupted connectivity in IoT systems. For wildlife preservation, this technology enables automated alert systems to monitor environmental conditions, track animal movements, and report critical events in real-time. By leveraging 4G modules with SMS capabilities, devices can send automated alerts and receive instructions, ensuring that even in isolated regions, conservation efforts are not hindered by lack of modern network infrastructure. This integration of automation and communication helps enhance the effectiveness of monitoring systems in remote wildlife areas, offering a reliable solution for protection and research.
Hardware Preparation
| Raspberry Pi 5 | Raspberry Pi 4G LTE CAT4 HAT |
|---|---|
 |  |
The Setup
Sending an SMS Using QCOM Tool on Windows
Step 1: Setup the Module
- Plug in the Module
- Connect the module to your Windows PC via USB. Make sure the DIP switches are positioned in the correct order. In this case, all switches are set to 0, which means they are disabled.
- Turn on the Module
- Press the power button on the module.
- Verify Communication Ports
- Ensure that the drivers are installed correctly. You should see the COM ports listed in the Windows Device Manager.
Step 2: Open the QCOM Interface
- Install and Launch QCOM
- Download and install the QCOM v1.6 software.(if you not)
- Launch the tool on your PC.
- Configure the COM Port
- Select the COM port associated with the module (e.g., COM3) in the QCOM interface.
- Set the baud rate to the recommended value (e.g., 9600).
Step 3: Send an SMS
Test the Module Communication
- In the command input box, type the following command:
AT
- Click Send.
- The module should respond with:
OK
- This confirms that the module is ready.
Set SMS Mode
- Type the following command to set the SMS mode to text:
AT+CMGF=1
- Click Send.
- The module should respond with:
OK
Check SMSC Number
- Query the SMSC (Short Message Service Center) number from the SIM card by typing:
AT+CSCA?
- Click Send.The response should be something like:
+CSCA: "+1234567890",145
OK
- If no SMSC is set, contact your service provider to obtain the correct number, and set it using:
AT+CSCA="+1234567890"
Compose and Send SMS
- Type the command to initiate an SMS:
AT+CMGS="+9876543210"
Replace +9876543210 with the recipient's phone number.
Click Send.
The QCOM interface will display:
>
- Now, type your message (e.g., Hello!) in the text box.
Submit the SMS
- Press Ctrl + Z or use the QCOM interface option to send the SMS.
- The module will respond with:
+CMGS: 25
OK
- This indicates that the SMS was sent successfully.
Step 4: Verify the SMS
- Check the recipient’s phone to ensure the message has been received.
Sending an SMS Using Minicom on Raspberry Pi
Assuming you have installed the drivers and booted the module correctly. If not, please follow this guide.
Step 1 :Open Minicom
If the necessary drivers for communicating with AT commands are not installed, you will need to install them
sudo minicom -D /dev/ttyUSB2
Step 2: Follow the Commands in the Table
| Command | Response | Explanation |
|---|---|---|
ATE | OK | Enable echo to see typed commands in Minicom. |
AT | OK | Checks module readiness. |
AT+CMGF=1 | OK | Sets the SMS mode to Text Mode. |
AT+CSCA? | +CSCA: "+1234567890",145 | Queries the SMSC (Short Message Service Center) number from the SIM. |
AT+CMGS="+94712222803" | > | Prepares the module to accept the message content for the specified recipient. |
(Type the message: Hello!) | (No response) | Type the message content. |
(Press Ctrl+Z) | +CMGS: 25 OK | Sends the message. The module confirms with +CMGS and the message reference ID. |
Python Script for Send Massages
import serial
import time
# Configure the serial port
SERIAL_PORT = "COM7" # Replace with your module's COM port (e.g., COM3 on Windows, /dev/ttyUSB2 on Linux)
BAUD_RATE = 9600 # Adjust to the baud rate of your GSM module
# SMS details
SMSC_NUMBER = "+9477000000" # Replace with your carrier's SMSC number in international format
RECIPIENT_NUMBER = "+94712222813" # Replace with the recipient's phone number in international format
MESSAGE = "Hello, this is a test message from Python!"
def send_at_command(command, expected_response="OK", timeout=3):
"""Send an AT command to the GSM module and wait for a response."""
ser.write((command + "\r").encode())
time.sleep(timeout)
response = ser.read_all().decode()
print(f"Command: {command}\nResponse: {response}")
return expected_response in response
try:
# Open the serial connection
ser = serial.Serial(SERIAL_PORT, BAUD_RATE, timeout=1)
time.sleep(2) # Allow the module to initialize
# Test communication with the GSM module
if not send_at_command("AT"):
raise Exception("GSM module not responding. Check the connection.")
# Set SMSC number (optional, only if needed)
if not send_at_command(f'AT+CSCA="{SMSC_NUMBER}"'):
raise Exception("Failed to set SMSC number.")
# Set SMS to text mode
if not send_at_command("AT+CMGF=1"):
raise Exception("Failed to set SMS mode to text.")
# Send SMS
if not send_at_command(f'AT+CMGS="{RECIPIENT_NUMBER}"', ">"):
raise Exception("Failed to initiate SMS sending.")
# Provide the message content and send Ctrl+Z to finalize
ser.write((MESSAGE + "\x1A").encode()) # Ctrl+Z is sent as '\x1A'
time.sleep(5) # Wait for the module to send the SMS
response = ser.read_all().decode()
print(f"SMS Send Response: {response}")
if "OK" in response:
print("SMS sent successfully!")
else:
print("Failed to send SMS. Check the module or command syntax.")
except Exception as e:
print(f"Error: {e}")
finally:
if ser.is_open:
ser.close()
Receiving SMS Messages Using AT Commands on Windows Environment
This explains how to receive and read SMS messages using AT commands step-by-step. Follow these commands in the order listed.
Assuming you have installed the drivers and booted the module correctly. If not, please follow this guide.
Step 1: Set SMS Mode to Text
Use the AT+CMGF=1 command to set the GSM module to Text Mode for easier SMS handling.
Command:
AT+CMGF=1
Expected Response:
OK
Step 2: Check Current Message Storage
Use the AT+CPMS? command to check the current message storage configuration.
Command:
AT+CPMS?
Expected Response: +CPMS: "SR",0,5,"MT",19,255,"MT",19,255 OK
Explanation:
SR: Status Report storage (e.g., SMS delivery reports).MT: Mobile Terminal memory (SIM and module storage). In this example,"MT" contains 19 stored messages out of a capacity of 255.
Step 3: Switch Message Storage to "MT"
To access the messages in the Mobile Terminal memory, switch the storage to "MT" using AT+CPMS="MT".
Command:
AT+CPMS="MT"
Expected Response:
+CPMS: 19,255,19,255,19,255 OK
Explanation
- 19,255: 19 messages are currently stored, and the storage has a capacity for 255 messages.
Step 4: List All Stored Messages
Retrieve all messages stored in the selected memory using the AT+CMGL="ALL" command.
Command:
AT+CMGL="ALL"
Expected Response:
+CMGL: 1,"REC UNREAD","+1234567890","","20/12/05,10:44:12+32" Hello, this is a test message! +CMGL: 2,"REC READ","+9876543210","","20/12/05,10:45:12+32" Another test message! OK
Explanation:
- +CMGL: 1: Index of the first message.
- "REC UNREAD": Status of the message (Unread).
- "+1234567890": Sender's phone number.
- Hello, this is a test message!: Message content.
Step 5: Read a Specific Message
To read a specific message by its index (e.g., index 1), use the AT+CMGR=|index| command.
Command:
AT+CMGR=1
Expected Response:
+CMGR: "REC UNREAD","+1234567890","","20/12/05,10:44:12+32" Hello, this is a test message! OK
Explanation:
REC UNREAD: The message is marked as unread.+1234567890: The sender's phone number.- Hello, this is a test message!: The message content.
Receiving SMS Messages Using Minicom on Raspberry Pi
Assuming you have installed the drivers and booted the module correctly. If not, please follow this guide.
Step 1 :Open Minicom
sudo minicom -D /dev/ttyUSB2
Step 2: Follow the Commands in the Table
| Step | Command | Response Details | Purpose/Explanation |
|---|---|---|---|
| 1 | ATE | OK | Enables echo to see typed commands in the terminal. |
| 2 | AT+CMGF=1 | OK | Sets the SMS mode to Text Mode for easier SMS handling. |
| 3 | AT+CPMS? | +CPMS: "SR",0,5,"MT",19,255,"MT",19,255 OK | Checks the current message storage. "SR": Status Reports. "MT" (Mobile Terminal): Contains stored messages on the SIM and module. |
| 4 | AT+CPMS="MT" | +CPMS: 19,255,19,255,19,255 OK | Switches the message storage to "MT" (Mobile Terminal). 19,255: Indicates 19 stored messages out of 255 available slots. |
| 5 | AT+CMGL="ALL" | +CMGL: 1,"REC UNREAD","+1234567890","","20/12/05,10:44:12+32" Hello, this is a test message! +CMGL: 2,"REC READ","+9876543210","","20/12/05,10:45:12+32" Another test message! OK | Retrieves all messages stored in the selected memory. "REC UNREAD": Unread message. +1234567890: Sender's phone number. |
| 6 | AT+CMGR=1 | +CMGR: "REC UNREAD","+1234567890","","20/12/05,10:44:12+32" Hello, this is a test message! OK | Reads a specific message by its index (e.g., 1). "REC UNREAD": Indicates the message is unread. Hello, this is a test message!: Message content. |
Resources
[Web Page] LTE EG25-G
[Web Page] AT Commands Manual V2.0
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