How to make something like a PBX on a computer and USB modems?

Question

USB

I want to make something like a mini-PBX to receive calls from different SIM cards and record calls on a computer. As an option, they suggest using usb-modems in the right amount, inserting them into the hub ... and then I don’t know :)
The topic is generally third-party for me, but I want to try my hand.
Be kind - poke your nose at the materials, because Google gives out either not what you need, or very expensive and professional.
Need angrily and cheaply.
Thank you!

Answer 1

Somehow so .