On Dec 4, 4:57 am, "Daniel W. Rouse Jr."
wrote:
In the area I am in--on frequency 151.1900 (CDF/Cal Fire dispatch, Monte
Vista), sometimes a radio transmission will be preceded by several DTMF
tones (touch-tone phone button tones). On other occasions, a radio
transmission will be preceded by two musical tones, about 1 second each,
with the first tone being higher than the second tone, almost sounds like
high pitched fog-horn type tones.

Is there any significance to this?

Check this link:
http://en.wikipedia.org/wiki/Selective_calling

The site has some sample audio files you can compare with.

-Bill