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

Steve Underwood steveu at coppice.org
Fri Dec 12 10:01:44 MST 2003

Alastair Maw wrote:

> 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.

Its actually DPSK or QAM (depending on the bit rate), not FSK. FSK is 
used for the control information, but not for the image.


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