I didn't realise people could ring them!
We were there in Oct and one day I popped into the restrooms in the UK pavilion beside the phone booths. My mum didn't go in and waited outside for me. When I came out, she was very excited, saying that one of the phones had rang just as a guy was walking past, so he picked it up, started laughing, then hung up and walked off chuckling.
She was really excited and made us wait around for ages to see if it happened again!
Is it only park fans etc who ring them? Or do maybe Disney make them ring with a pre-recorded character message (like the ones you get to your room when you have a birthday)?