I read a very intriguing book earlier this year titled “Will Storr vs. the Supernatural”, where a young British journalist, as named in the title, decides to investigate the paranormal for himself.
He relates a very compelling set of experiences he has along the way and notes certain patterns that seem to recur across different manifestations. One of them is that the phenomena seem to occur around 3:30 am. Note the time in the article at which the phone calls ceased.
FWIW, Will Storr commenced his project as a skeptic and emerged from it as something else, just as Nora Blum did when she researched and wrote her book “The Ghost Hunters”.
I had heard paranormal things always happen at 3 am. Guess which time I frequently awaken in the middle of the night. lol. Always between 3:01 and 3:15 a.m.