Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!accuvax.nwu.edu!nucsrl!telecom-request
From: David E A Wilson <david@cs.uow.edu.au>
Newsgroups: comp.dcom.telecom
Subject: Re: Telephone/Fax Switch Boxes and Ringback Tone
Message-ID: <10349@accuvax.nwu.edu>
Date: 2 Aug 90 07:20:28 GMT
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Organization: Dept of Computer Science, University of Wollongong, Australia
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X-Telecom-Digest: Volume 10, Issue 536, Message 12 of 15


kitty!larry@uunet.uu.net (Larry Lippman) writes:

>Such an audio path only
>existed when audible harmonics from ringing current were coupled back
>to the calling party using a capacitor to provide ringback tone.  Such
>ringback tone varied in intensity with the called party loop length
>and number of connected ringers, creating a disadvantage.  The use of
>the CCITT 440/480 Hz tones for ringback required a separate ringback
>tone generator and a different circuit which no longer created the
>above audio path.  Most No. 5 XBAR CO's were modified during the
>1960's to provide the above precise ringback tone.

Here in Australia, I have noticed that with my parents phone, the ring
sound that the caller gets depends on the phone plugged into the
socket (phones that chirp and phones that ring a bell sound different
to the caller).

Would this tend to indicate the vintage of their exchange?


David Wilson	Dept Comp Sci, Uni of Wollongong	david@cs.uow.edu.au