(Update below from The 9-pin Guy)
I've connected to BBSs recently but only via Wi-Fi. Now I have the luxury of the real copper wire POTS phone line for the fax, I can try using the Commander X16's new serial network card to connect to a BBS just as we used to - via dial-up!
Your ad-free early access: https://youtu.be/y1X-1ziXr0s
And for those who watched it, we did hear back from David just now:

Next week we'll be curating and filming The ЯRetro Show, plus either then or the following week I plan to drop a Quick Bytes your way all to do with getting my original family 50Hz stereo system working on the 60Hz power here, without singers sounding like chipmunks any more, thanks to a harebrained idea I've come up with. I wonder if it'll work...
Your friend in retro, Perifractic