When JF went to register at the main desk, he was told that his mother had called and left a number for him to return the call. Of course Mrs. Frid has been dead for twenty years and it was a ruse some fan was using to get JF to call him or her. It was amusing to say the least.
How bizarre. And how could anyone possibly think they could get away with something like that? :- I mean, even factoring out the fact that Frid's mom passed away many years ago, if the person left a number to call, Frid would have instantly recognized it as a number his mother wouldn't be likely to be reached at, so why would he even call it? And if they didn't leave a number, well, Frid would have called the number that he knew she could be reached at, so they most definitely wouldn't have received a call from him. In fact, if it was me, I would have called the number I knew my mom could be reached at either way and would have completely ignored any number that might have been left in the message unless I couldn't reach her any other way.
Although, there's also the alternative that the person who left the message knew full well that Frid's mom had passed (after all, that would be 99.99% likely given Frid's own age), they never expected a call back, and they simply did the whole thing as a cruel joke. People are strange - and twisted...