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<DIV><FONT face=Arial size=2><FONT face="Times New Roman" size=3>> -----
Original Message ----- <BR>> From: "Alastair Maw" <</FONT><A
href="mailto:asterisk@almaw.com"><FONT face="Times New Roman"
size=3>asterisk@almaw.com</FONT></A><FONT face="Times New Roman"
size=3>><BR>> To: <</FONT><A
href="mailto:asterisk-users@lists.digium.com"><FONT face="Times New Roman"
size=3>asterisk-users@lists.digium.com</FONT></A><FONT face="Times New Roman"
size=3>><BR>> Sent: Friday, December 12, 2003 4:58 PM<BR>> Subject: Re:
[Asterisk-Users] FAX, IAX and *....Maybe I'm dreaming...:-)<BR>> <BR>>
<BR>> > On 12/12/03 13:56, Dan wrote:<BR>> > > This is because
the fax is transmitted using the audio stream.<BR>> > > It is not
related to the signaling protocol (SIP/IAX etc.) but to the<BR>>
audio<BR>> > > codec used.<BR>> ><BR>> > Fax uses FSK
modulation to transmit the data. If you compress this in a<BR>> > lossy
way (GSM, MP3, whatever) then the integrity of the data is<BR>> > affected
(more or less seriously depending on the codec used). Fax<BR>> > machines
are generally quite picky, so compressing faxes is unlikely to<BR>> >
work.<BR>> ><BR>> > I'm wondering why on earth you want to push fax
data over a VoIP link at<BR>> > all. Fax compression isn't very
efficient.<BR>> <BR>> Who wants that???<BR>> By fax data I mean the
data contained in a fax (basically a picture file),<BR>> not the fax data
audio stream.<BR>> It can be converted (GIF or JPG) then sent reliable over a
slow IP link.<BR>> Just a special codec at both ends, able to pass the data
to the fax app or a<BR>> fax machine connected to a TDM400/ AT or
whatever.<BR>> <BR>> > It would be much less<BR>> > bandwidth
intensive to decode the fax and send it over as proper data<BR>> > rather
than audio, compressed using gzip/gif/png/something else.<BR>> <BR>> This
is exactly what would be great to have it.</FONT></FONT></DIV>
<DIV><FONT face=Arial size=2><FONT face="Times New Roman"
size=3></FONT><BR><FONT face="Times New Roman">The question asked here,</FONT>
"<FONT face="Times New Roman" size=3>why on earth you want to push fax data over
a VoIP link at<BR>all. Fax compression isn't very efficient." may speak volumes
about the future role of VOIP. My plans are to role out a VOIP connection to
thousands of Customers. Many have legacy fax equipment. Am I to assume that they
will toss out their fax equipment and join the PC based faxing crowd? I don't
think I can control this. If I am going to offer an aternative to the legacy
wire providers then I have to offer a comparable service. One that for example
allows a customer to use a legacy fax machine in the same
way.</FONT></FONT></DIV>
<DIV><FONT face=Arial size=2><FONT face="Times New Roman"
size=3></FONT></FONT> </DIV>
<DIV><FONT face=Arial size=2><FONT face="Times New Roman" size=3>If this thought
sidetracks the intent of this thread, you have my apologies, but I do think that
legacy fax functionality is essential.</FONT></FONT></DIV>
<DIV><FONT face=Arial size=2><FONT face="Times New Roman"
size=3></FONT></FONT> </DIV>
<DIV><FONT face=Arial size=2><FONT face="Times New Roman"
size=3>Jeff</FONT></DIV>
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