[Asterisk-Users] T.38 fax summary

[Martijn van Oosterhout]

On Sun, Feb 27, 2005 at 04:14:46PM +0800, Steve Underwood wrote:
> Questions keep comming up about this, so I started writing something at 
> http://www.soft-switch.org/foip.html . I think I covered the FAX over 
> VoIP issues fairly completely. T.37 is pretty simple to explain. There 
> is rather more to say about T.38, but at least this is a start. If 
> anyone wants to suggest corrections or additions, just blurt them out.

Hi,

I read it and found it very enlightening. I do have one question
regarding "Modems don't like relativity". It says modems need a
constant delay; is there a limit to what it can handle. For example,
would it be possible to configure a jitterbuffer right at the endpoint
before the fax to put a constant delay of 1 second relative to the
sender. This should be enough time to weed out any jitter. Basically,
fix the jitterbuffer so the delay is constant. If a fax can handle a
constant delay of up to a second you're home.

Maybe also allow people to setup a jitterbuffer to do a special
interpolation for fax, which might just amount to sending a special
tone representing zeros. Is there a possiblity of creating a app
allowing people to configure the jitterbuffer for a particular call?

In any case, if it can't be done this way, could you explain why?

-- 
Martijn van Oosterhout
Ecomtel Pty Ltd