Today I set a dial up connection between two USB modems I had around on virtual machines running Windows 98SE. I wanted to go older, but 98SE was the earliest with driver support.
With some tinkering, there is no battery or expensive line simulator, ring simulator or any other simulator. I can successfully access the Internet from VM #2 using web from the NIC on VM #1. Just the two modems and a plain phone line between them.
Here's some screenshots of VM #2!

Unchecked Wait for Dial Tone Before Dialing option



Still remember my old ISP's dial up number like it was yesterday. It's only natural to use it 😀









Overall, I'm happy it works. I know it's nothing special, but I'm pleased to get it down to such a simple process that I can hopefully use it reliably on an actual machine on one end with a proper ISA/PCI/Serial modem, and a VM with USB modem on the other from my main PC.