I believe this could quite well be true, as Slip said such a number isn't hard to get a hold of:

Contacting the White House

As ghost stated "So I jokingly said that the next number posted I was going to call." chances are the people were dropping numbers that were of a similar nature in hope someone would call them. Then after ghost said that, the jokers could have thought about pulling a fly one on ghost himself, which it seems they did. So chances are it did in fact happen.