How do I get the next three episodes of the original Quake, when it says I have to register but...?

I downloaded a free version online, and I managed to play it for the first time in years. Despite the fact that it doesn't have any sound (it's disabled, and I'm working to fix that), I still enjoy it, but now that I've beaten the first episode, I want to play the second, third, and fourth, yet it says I have to register by calling a number. I'm not even going to bother calling it - I doubt anybody's still registering a 13 year old computer game. The hotline's probably long since expired anyways. So is there any way that I can still be able to play the next three episodes?