[asterisk-users] Rxfax and Txfax on Asterisk 1.4

[Lee Howard]

Ardjan Zwartjes wrote:

>One thing that's important to mention here: We get unpredictable results
>if the fax is transmitted entirely over VOIP, if the fax passes a
>regular telephony channel once it works fine but if it's purely VOIP,
>transmission errors occur. This is probably a timing problem, but we
>haven't been able to solve it yet
>

It's not a timing problem, it's a "that just happens when you do faxing 
over typical VoIP channels" problem.  The reason it happens is because 
of jitter... and more specifically, packet loss.  On UDP communications 
packets are not retransmitted if they get dropped by a router or switch 
or hub.  You can't just take a data stream and chop out small chunks of 
it here and there and expect the receiving end to be okay with it.

Lee.