SMS4J

Library for sending SMS via USB modem (AT commands over serial) in Java 17. One instance manages one modem on a given port. Currently supports ZTE MF710.

Requirements

• Java 17
• jSerialComm (included as Maven dependency) for serial communication

Finding the modem port

• Windows: Device Manager → Ports (COM & LPT), or use a port enumerator. Typical name: COM3, COM4, etc.
• Linux: Often /dev/ttyUSB0 or /dev/ttyACM0 when the modem is plugged in. List with ls /dev/tty*.

You can also list available ports in code with jSerialComm:

import com.fazecast.jSerialComm.SerialPort;

for (SerialPort p : SerialPort.getCommPorts()) {
    System.out.println(p.getSystemPortName() + " - " + p.getPortDescription());
}

Usage

Auto-detect driver (default): When you only pass the port, the library sends AT then ATI to detect the modem model and selects the driver from a registry (e.g. MF710 → ZTE MF710 driver).

import balbucio.sms4j.Sms4j;
import balbucio.sms4j.SmsSendResult;
import balbucio.sms4j.Sms4jException;
import balbucio.sms4j.PortInUseException;

// One instance = one modem; driver is selected automatically via ATI
Sms4j modem = new Sms4j("COM3");

try {
    modem.open();
    SmsSendResult result = modem.sendSms("+5511999999999", "Hello from SMS4J");
    if (result.isSuccess()) {
        System.out.println("Sent. Ref: " + result.getMessageRef());
    } else {
        System.out.println("Failed: " + result.getErrorMessage());
        System.out.println("Raw: " + result.getRawResponse());
    }
} catch (PortInUseException e) {
    System.err.println("Port in use: " + e.getMessage());
} catch (Sms4jException e) {
    System.err.println("Error: " + e.getMessage());
} finally {
    modem.close();
}

Manual driver: If auto-detect fails or you want to force a specific driver, pass a factory:

import balbucio.sms4j.Sms4j;
import balbucio.sms4j.modem.zte.ZteMf710Driver;

Sms4j modem = new Sms4j("COM3", ZteMf710Driver::new);
modem.open();
// ...
modem.close();

Integration tests

Some tests require a modem and are skipped unless configured:

Config	Source	Example
Port	sms4j.test.port (system property)	-Dsms4j.test.port=COM3
Phone (for send test)	sms4j.test.phone (property) or SMS4J_TEST_PHONE (env)	-Dsms4j.test.phone=+5511999999999

Example with real modem and SMS send:

mvn test -Dsms4j.test.port=COM3 -Dsms4j.test.phone=+5511999999999

Or set SMS4J_TEST_PHONE in the environment and only pass the port to Maven.

Encoding

SMS body is sent in UTF-8. The modem may use GSM 7-bit or other encoding depending on the character set; for extended characters, refer to your modem’s documentation.

License

This project is under the MIT License. See license.txt.

Dependencies:

• jSerialComm – LGPL (or commercial license). See the project for terms.