You need a GSM dongle "compatible" with Gammu : https://wammu.eu/phones/
Even if your dongle is not listed, it should works with.

If you need specific gammu settings to be added, feel free to open a PR or an issue.

For Docker, run it by executing the following commmand:

docker run \
    -d \
    --name sms2mqtt \
    --restart=always \
    --device=/dev/ttyUSB0:/dev/mobile \
    -e PIN="1234" \
    -e HOST="192.168.1.x" \
    -e PORT=1883 \
    -e PREFIX="sms2mqtt" \
    -e CLIENTID="sms2mqttclid" \
    -e USER="usr" \
    -e PASSWORD="pass" \
    domochip/sms2mqtt

For Docker-Compose, use the following yaml:

version: '3'
services:
  sms2mqtt:
    container_name: sms2mqtt
    image: domochip/sms2mqtt
    devices:
    - /dev/serial/by-id/usb-HUAWEI_HUAWEI_Mobile-if00-port0:/dev/mobile
    environment:
    - PIN=1234
    - HOST=10.0.0.2
    - PORT=1883
    - PREFIX=sms2mqtt
    - CLIENTID=sms2mqttclid
    - USER=mqtt_username
    - PASSWORD=mqtt_password
    restart: always

• device: Location of GSM dongle (replace /dev/ttyUSB0 with yours), it need to be mapped to /dev/mobile

NOTE: The /dev/ttyUSBx path of your GSM modem could change on reboot, so it's recommended to use the /dev/serial/by-id/ path or symlink udev rules to avoid this issue.

• PIN: Optional, Pin code of your SIM
• HOST: IP address or hostname of your MQTT broker
• PORT: Optional, port of your MQTT broker
• PREFIX: Optional, prefix used in topics for subscribe/publish
• CLIENTID: Optional, MQTT client id to use
• USER: Optional, MQTT username
• PASSWORD: Optional, MQTT password

The default {prefix} for topics is sms2mqtt.

To send SMS:

1. Publish this payload to topic sms2mqtt/send :
   {"number":" 33612345678", "text":"This is a test message"}
2. SMS is sent
3. A confirmation is send back through MQTT to topic sms2mqtt/sent :
   {"result":"success", "datetime":"2021-01-23 13:00:00", "number":" 33612345678", "text":"This is a test message"}

• ✔️ You can send SMS to multiple Numbers using semicolon (;) seperated list. A confirmation will be sent back for each numbers.
• ✔️ You cand send very long messages (more than 160 char).
• ✔️ You can send unicode messages containing emoji like : {"number":" 33612345678", "text":"It's working fine 👌"}
• ✔️ You can send very long messages containing emoji

Received SMS are published to topic sms2mqtt/received like this :
{"datetime":"2021-01-23 13:30:00", "number":" 31415926535", "text":"Hi, Be the Pi with you"}

• ✔️ You can receive long SMS messages
• ❌ You can't receive any MMS

• sms2mqtt/signal: A signal quality payload is published when quality change
  E.g. {"SignalStrength": -71, "SignalPercent": 63, "BitErrorRate": -1}

You need to have a look at logs using :
docker logs sms2mqtt

To update to the latest Docker image:

docker stop sms2mqtt
docker rm sms2mqtt
docker rmi domochip/sms2mqtt
# Now run the container again, Docker will automatically pull the latest image.

I want to thanks those repositories for their codes that inspired me :

• https://github.com/pajikos/sms-gammu-gateway : I have a Huawei dongle and I found out that gammu 1.39 works fine with it 👌
• https://github.com/pkropf/mqtt2sms