I'm currently writing another book that deals with my time living in a house with paranormal activity. In doing some research about ghost activity, I ran across an interesting report. I was already aware of such reports of phantom telephone rings that many think come from a recently passed loved one.
It is not a far stretch to think that a spirit could make a telephone ring. After all, there is plenty of cases where spirits have caused K2 meters to light up, or unknown voices are captured on a recorder, or some other device seems to be manipulated by an unseen entity.
There are even some cases of people hearing their passed love one speak on the line after a phantom phone call.