Send SMS via Node-Red without internet

Hi all curently im using an external service provider,twilio, to send SMS.
However, I would like to send SMS without using internet as the data is sensitive. Is there any hardware that I can interface with node red easily to send SMS using the traditional methods. e.g phone sending sms with sim card

You can have a phone with tasker or Automate installed. These can receive http or mqtt request locally, they can then parse the message and send sms from the phone directly.

I presume you could do this with a mobile adaptor plugged into the pc, along with appropriate software.

I use a Maestro GPRS Modem to achieve the same result. Quick look suggests telematic modems is a good search term.

It runs by sending AT commands over serial - there seems to be USB versions now. In my case, it is connected from another controller (not Node RED), but that is historic. I have used a USB to Serial convertor when testing.

They are comparatively expensive, but then this was for a mission critical solution. It has been running for years without failure. (There, that has jinxed it! :sweat_smile:)

I used to do this with an android phone running node-red via Termux. It sort of worked, Android phones seem to have issues if left on the charger 24/7

You know SMS is not secure right?

"Why SMS Text Messages Aren’t Private or Secure" Why SMS Text Messages Aren’t Private or Secure

I know. But top management people think the internet is extremely dangerous.