If you need send SMS using own GSM modem you can use Custom Protocols to instruct modem send messages.

To send SMS you need send a few AT-commands to modem. Unfortunately, sometimes they are vendor-specific and we can't built in support all modems into WebHMI. So we publish custom protocol that will help you understand the idea and adopt it for your modem.

Here is the sample protocol that will send message:

function createDevices ()
    addDevice({name = "SMS",  shift = 0, base = 10, xtraFields = {1, 5}});
end
 
function readRegister (reg, device, unitId)
    return "SMS";
end
 
function writeRegister (reg, device, unitId, newValue)
    sendString("AT+CPIN=\"0000\"\r");
    sendString("AT+CMGF=1\r");
    sendString("AT+CSMP=17,167,0,0\r");
    sendString("AT+CMGS=\"+" .. reg.addr .. "\"\r");
    sendString(newValue);
    sendString(string.char(26));
    return true; 
end