Eight hours ago I took a call on my phone (which is not a publicly listed number)
from someone identifying himself as from some educational services firm. He asked for me by name, but I let him know this unsolicited call was not wanted, in the midst of which he hung up on me. Now, the same number has left a "hang-up message", saying someone called and left no message. The caller's number registers as the one I've written above, which when I rang it three times to let whoever's at the other end know that I do not want to be contacted by them repeatedly says "Line busy". I'm not going to keep ringing them back but am concerned that (a) they got my number at all; and (b) threaten to become a nuisance caller. What can I do? (My email address is kjhaley @ bigpond.com)