Missed call from this number on my cellphone, returned call to get the disconnect message listed above

RECEIVED CALL FROM THIS # A FEW MINUTES AGO. COMPLETED MY COMPANY GREETING AND WAS MET WITH SILENCE AND THEN A CLICK. CALLED THE # BACK AND GOT THIS RECORDED MESSAGE " THE TOLL FREE NUMBER THAT YOU HAVE DIALED HAS BEEN DISCONNECTED. NO FURTHER INFORMATION IS AVAILABLE ABOUT THIS NUMBER, 027P".
HOW DOES SOMEONE CALL FROM A "DISCONNECTED" NUMBER?