Which still lives on today in cellular networks. At least up to LTE, I haven't looked lately to see if they're sticking around for 5G.

https://www.rfwireless-world.com/Terminology/modem-AT-comman...

If you are talking to one of those self-contained, postage stamp-sized GSM modules using a microcontroller, chances are there'll be a serial link to it, and it's listening to Hayes commands.

It's still there.

/me looks at this content-free page and then reads your comment

+++ATH0

ATDT

ATZ0E0M0L0&A0&D0&G0&K0&N1&U1

ATDT@;684-767-2676 (or any 767-XXXX, 555-XXXX is also fun)