albert@ucbarpa.Berkeley.EDU (Anthony Albert) (12/18/89)
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
albert@ucbarpa.Berkeley.EDU (Anthony Albert) (12/20/89)
Sorry about this. I don't have any idea how this ended up in this newsgroup. Anthony Albert ..!ucbvax!ucbarpa!albert albert@ucbarpa.Berkeley.EDU