This looks like it may have potential.
Windows or Linux.
Frank Arnold

----------  Forwarded Message  ----------
Subject: AUDIO CONFERENCING WITH LINUX
Date: Tue, 7 Aug 2001 23:00:54 -0700
From: Frank Arnold <[log in to unmask]>
To: Frank Arnold <[log in to unmask]>, Hans Anderson <[log in to unmask]>


------------------------------------------------------------------
MACHINEOFTHEMONTH: AUDIO CONFERENCING WITH LINUX

Here's a look at the other Nautilus project: an audio
conferencing package that has versions available for both
Linux and Windows. According to the author, it's easy to set up
and operates either over the 'net or with a direct connection
between two modems (for encrypted communications without the
special phone.)

COMPLETE STORY:
http://machineofthemonth.org/articles/a63/index.html

------------------------------------------------------------------
From:
http://www.lila.com/nautilus/
Nautilus is a program which allows two parties to hold a secure voice 
conversation. Released in May of 1995, it ran on ordinary phone lines using a 
pair of modems (one at each end). Version 1.5a added the ability to work over 
TCP/IP networks including the Internet (Unix versions only). Version 1.6a 
release was released in June of 1997, and was primarilly a bug fix release. 
Version 1.7a was released in September, 1998. In addition to some minor bug 
fixes, it adds support for 32-bit Microsoft Windows platforms including 
Windows 95, 98, and NT.

Information on where to obtain the latest release is available in the next 
section.

For more detailed information on the functionality and operation of Nautilus, 
check out the manual (needs updating). Please read the system requirements 
section before contacting the developers with problems. If you have questions 
or comments about Nautilus that are not answered in the manual, you may 
contact the developers by sending mail to the Nautilus developers list..
-------------------------------------------------------