Yes I think that's it!

Well, no, I have to say I don't understand what was accomplished there.

Maybe try this?

http://podsix.org/articles/pimodem/

No, that's really not what I mean.

I would like everyone to still use their retro computers and retro modems (!). Because no-one has land lines anymore, we would need some devices and software to emulate the land-line and telephone network over the internet (IP-protocol). Probably VoIP stuff.

I would like to ATDT9834982 and have that magically connect over the internet to some other guy's retro modem that has registered that number in this virtual telephone network over the internet. His modem would receive the proper ring indication and the BBS would ATA.

This should not depend on any telephone operators.

If someone wants to use a software modem, that would be fine, but real modems would be the point of this whole thing.