Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!sun-barr!decwrl!ucbvax!ucbarpa.Berkeley.EDU!albert
From: albert@ucbarpa.Berkeley.EDU (Anthony Albert)
Newsgroups: sci.electronics
Subject: Detecting telephone call progress tones
Keywords: telephone detect tone
Message-ID: <33315@ucbvax.BERKELEY.EDU>
Date: 19 Dec 89 22:49:32 GMT
Sender: usenet@ucbvax.BERKELEY.EDU
Reply-To: albert@ucbarpa.Berkeley.EDU.UUCP (Anthony Albert)
Organization: University of California, Berkeley
Lines: 20
References:

I'm looking for an easy to implement way to detect the receiver off-hook
warning tone.  Apparently it is made up of 1400 + 2060 + 2450 + 2600 Hz
tones that pulse on and off for .1 sec.  Are there chips that do this sort
of thing?  Can I be guaranteed that phones left off the hook all over the US
will receive this tone?

What books and/or sources are there that deal with telephone electronics?
Sources for things like special purpose ICs and anything else specific to 
telephones.

Thanks,
Anthony

				Anthony Albert
				..!ucbvax!ucbarpa!albert
				albert@ucbarpa.Berkeley.EDU

				Anthony Albert
				..!ucbvax!ucbarpa!albert
				albert@ucbarpa.Berkeley.EDU