[jaclaz]

Many years ago I knew someone (an electrical engineer by trade) that modified a standard/ubiquitous Panasonic telephone answering machine connecting it to his home thermostat, he used the code to hear messages to switch the heat on.

You don't need the internet, nowadays the equivalent would most probably be something like :

https://www.ezyswitch.co.nz/

[gkop]

Both voice calls and SMS are routed over the internet today, though…