Source : Free On-Line Dictionary of Computing

whalesong
     
        The peculiar clicking and whooshing sounds made by a {PEP}
        {modem} such as the {Telebit} {Trailblazer} as it tries to
        synchronise with another PEP modem for their special
        high-speed mode.  This sound isn't anything like the normal
        two-tone handshake between conventional modems and is
        instantly recognizable to anyone who has heard it more than
        once.  It sounds, in fact, very much like whale songs.  This
        noise is also called "the moose call" or "moose tones".