Try this out one night, but be VERY, VERY careful, ring voltage can surprise you:

If you have access to the point where the phone lines enter the house, go there and check the box out. This is called the demarcation point, and has a module inside to allow the telco to remote test your line(s). There should be a modular plug just like the ones inside your house, and a pair of terminals with wires attached. Some older units just have the terminals, and there should be a pair for each phone line. Disconnect the line by either unplugging the mod plug, or loosen the terminals slightly and lift the wire(s). If you have more than one phone jack, you may have more than just the one pair of wires. Pay attention to how things are hooked up, and make a drawing if necessary (recommended).

Now go to bed. If you are not wakened by the ring, you know that there is something inside the dwelling that is hooked up to the line. You can try to trace the wires (good luck!) or just reconnect one pair at a time, test the phones to see which jacks work, and label the wires. If you find a pair of wires that don't go to anything, leave them off for now, and see if the phantom ring goes away.

If you are sure you have disconnected your line(s) and the ring still occurs, I will have to scratch my head some more. Are you in a house or condo or townhome or apartment? Is the building old or new or had recent work done? More data is useful.

I think the line test is the most probable, but with the phone unplugged, you shouldn't be able to hear it.

Good luck!