<div>Interseting you mentioned this for I was having to look this info up this week as well and found this article:</div>
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<div><a href="http://www.cisco.com/univercd/cc/td/doc/product/software/ios121/121newft/121t/121t3/dt_t38fx.htm">http://www.cisco.com/univercd/cc/td/doc/product/software/ios121/121newft/121t/121t3/dt_t38fx.htm</a></div>
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<div>What I understood is that it varies depending on the fax rate command. If you use fax rate voice it will take 64k, but if you use faxrate 9600 it only uses 24k.</div>
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<div><strong>Excerp:</strong></div>
<div><strong>Note</strong> The fax call will not get compressed using the ip rtp header-compression command, because User Datagram Protocol (UDP) is being used and not Real-time Transport Protocol (RTP). For example, 9600 fax call will take about 24 kbps.
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<div><span class="gmail_quote">On 6/3/05, <b class="gmail_sendername">Brian Turnbow</b> <<a href="mailto:b.turnbow@twt.it">b.turnbow@twt.it</a>> wrote:</span>
<blockquote class="gmail_quote" style="PADDING-LEFT: 1ex; MARGIN: 0px 0px 0px 0.8ex; BORDER-LEFT: #ccc 1px solid"><br>
<p><font face="Arial" size="2">Hello All, </font><br><font face="Arial" size="2">I am look ing to deploy a SIP network that needs to support fax and looking into t.38 I found </font></p>
<p><font face="Arial" size="2">SIP T.38 Fax Relay </font></p>
<p><font face="Tahoma" size="2">•</font><font face="Arial" size="2">T.38 fax relay requires a 64-kbps transmission rate, the same amount of bandwidth as a voice call with the G.711 codec. </font></p>
<p><a onclick="return top.js.OpenExtLink(window,event,this)" href="http://www.cisco.com/en/US/products/sw/iosswrel/ps1839/products_feature_guide_chapter09186a00800b5dce.html" target="_blank"><u><font face="Arial" color="#0000ff" size="2">
http://www.cisco.com/en/US/products/sw/iosswrel/ps1839/products_feature_guide_chapter09186a00800b5dce.html</font></u></a> </p><br>
<p><font face="Arial" size="2">Do you need 64k for a fax transmission with via sip using a cisco gateway ? </font></p>
<p><font face="Arial" size="2">Thanks</font> <br><font face="Arial" size="2">Brian</font> </p><br>_______________________________________________<br>cisco-voip mailing list<br><a onclick="return top.js.OpenExtLink(window,event,this)" href="mailto:cisco-voip@puck.nether.net">
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<br><br><br></blockquote></div><br><br><br>-- <br><br>Nick Marus<br><a href="mailto:nmarus@gmail.com">nmarus@gmail.com</a><br>homepage: <a href="http://www.nicholasmarus.com">http://www.nicholasmarus.com</a><br>