You are correct. I took their press release to mean that they had a special page for emergency services. Their videos make it clear they’re just sending a generic text – https://what3words.com/mapsitecontrol/

As it happens, I did build a similar site many years ago when working for a telco. It was half-a-dozen lines of JavaScript, POSTing back to a server. I’ll see if I can drag out the code.