Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!clyde.concordia.ca!uunet!tut.cis.ohio-state.edu!ucbvax!ucbarpa.Berkeley.EDU!albert
From: albert@ucbarpa.Berkeley.EDU (Anthony Albert)
Newsgroups: news.groups
Subject: Detecting telephone call progress tones
Keywords: virtual worlds virtual reality cyberspace artificial reality
Message-ID: <33267@ucbvax.BERKELEY.EDU>
Date: 18 Dec 89 01:26:16 GMT
References: <14670@well.UUCP>
Sender: usenet@ucbvax.BERKELEY.EDU
Reply-To: albert@ucbarpa.Berkeley.EDU.UUCP (Anthony Albert)
Organization: University of California, Berkeley
Lines: 16

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