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<H2><A NAME="echo"></A>Echo servers</H2>
<P>Setting up <i>Speak Freely</i> usually involves fiddling around
with different <A HREF="compresswhy.htm">compression modes</A>,
<A HREF="connproperties.htm">connection options</A>, and,
perhaps, <A HREF="workarounds.htm">workarounds for bugs</A> in
your network and audio drivers. Getting everything set right
for your machine, network connection, and audio hardware
usually requires testing various modes in real connections.
It's irritating to get lots of "Hello, can you hear me?" calls
which consume 10 or 15 minutes of your time each as a total
stranger asks you to report on various settings on their
end.</P>
<P>Echo servers allow you to run tests on your own, 24 hours a
day, without disturbing others. An echo server is simply a
machine running a special copy of <A
HREF="sfunixmanpage.htm"><i>Speak Freely</i> for Unix</A> which,
rather than playing audio it receives on the speaker, stores it
in memory for 10 seconds and then sends it back to the machine
which sent it, using the same compression and encryption
modes. Before you experiment with an echo server, you might
want to try <A HREF="loopback.htm">local loopback</A> to verify
that your sound hardware is working properly before venturing
onto the network.</P>
<P>To run a test, create a new <A
HREF="newconnection.htm">connection</A> to one of the echo
servers listed below. Unless you deliberately want to
experiment with long distance transmission, it's usually best
to connect to a nearby server. Then select whatever
compression and other modes you want to try and transmit a
short (less than 10 second) test message, such as the
traditional "Testing: one, two three, four" and go back to
receive mode. Ten seconds after the start of your test
message, plus however long it takes the network to transmit the
sound in both directions, you'll hear your test message
returned by the echo server. If the audio is broken up, you
may have to select different modes (or it may simply indicate
traffic on the network between you and the server is so
congested everything is being delayed).</P>
<p>
A public <i>Speak Freely</i> echo server is available at the site:
<p>
<pre>
<b>echo.fourmilab.ch</b> Switzerland (see note below)
</pre>
<P>As with everything on the Internet, servers are in a
constant state of flux. For up to date information on
available echo servers consult the <i>Speak Freely</i> World-Wide Web
page:
<B><a href="http://www.fourmilab.ch/speakfree/windows/">http://www.fourmilab.ch/speakfree/windows/</a></B>.
<P>The <B>echo.fourmilab.ch</B> server shares its
connection to the Internet with the busy Web site
<B>www.fourmilab.ch</B>. As a result, you may get break-ups
when testing with that site purely because the Web traffic has
saturated the capacity of the site's Internet connection.
Other servers may have similar constraints, which often vary
with the time of day and day of the week.</P>
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