Paula Abdul FIRED from 'X Factor' ... And Simon Hasn't Called

Paula Abdul got the ax from "X Factor" ... TMZ has learned.

It's a stunning development, given that Simon Cowell personally recruited Paula after she was booted from "American Idol."

Sources also tell TMZ ... Paula got the news from a lawyer connected with the show, and has yet to hear from Simon.

Paula's pink slip now sits on top of those delivered to Nicole Scherzinger and Steve Jones.

Our sources say Simon has not found replacements for the cast members who got booted.