Phone Computer / So They're On A Cell And I'm On Mic

Any way to simply have someone phone my computer such that they're on a cell and I'm on my mic? It seems like such a simple thing for this day and age, but my attempt at a Google search is resulting in things that aren't exactly what I mean, such as where I can phone them first, but would have to incur charges, as if I'm using a cell myself instead of a mic. Any way, a site, or a software, to make such a setup work? To be clear, someone using a cell phone--not a mic and not a computer--would somehow "phone" my computer/a software I have, and I would hear them through the speakers as usual and communicate by my PC mic--not a phone and not a cell.