Re: [Asterisk-Users] FAX, IAX and *....Maybe I'm dreaming...:-)

[ProvoCityPower]

> ----- Original Message ----- > From: "Alastair Maw" <[EMAIL PROTECTED]> > To: <[EMAIL PROTECTED]> > Sent: Friday, December 12, 2003 4:58 PM > Subject: Re: [Asterisk-Users] FAX, IAX and *....Maybe I'm dreaming...:-) > > > > On 12/12/03 13:56, Dan wrote: > > > This is because the fax is transmitted using the audio stream. > > > It is not related to the signaling protocol (SIP/IAX etc.) but to the > audio > > > codec used. > > > > Fax uses FSK modulation to transmit the data. If you compress this in a > > lossy way (GSM, MP3, whatever) then the integrity of the data is > > affected (more or less seriously depending on the codec used). Fax > > machines are generally quite picky, so compressing faxes is unlikely to > > work. > > > > I'm wondering why on earth you want to push fax data over a VoIP link at > > all. Fax compression isn't very efficient. > > Who wants that??? > By fax data I mean the data contained in a fax (basically a picture file), > not the fax data audio stream. > It can be converted (GIF or JPG) then sent reliable over a slow IP link. > Just a special codec at both ends, able to pass the data to the fax app or a > fax machine connected to a TDM400/ AT or whatever. > > > It would be much less > > bandwidth intensive to decode the fax and send it over as proper data > > rather than audio, compressed using gzip/gif/png/something else. > > This is exactly what would be great to have it. The question asked here, "why on earth you want to push fax data over a VoIP link at 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.   If this thought sidetracks the intent of this thread, you have my apologies, but I do think that legacy fax functionality is essential.   Jeff