[Asterisk-Users] T.38 Faxing -> at astricon ?

[Steve Underwood]

Roger Schreiter wrote:

> Roy Sigurd Karlsbakk schrieb:
>
>> ...
>> see http://soft-switch.org/foip.html for a brief explaination of why  
>> this generally doesn't work...
>
>
>
> Hi,
>
> maybe one should update this link.

Update it in what way?

>
> I think, you agree, that VoIP is somewhat similar to ISDN, as it
> transports analog audio data in a digitally coded way.

VoIP is not every remotely in the same ballpark as ISDN, which makes the 
rest of what you say below meaningless. ISDN has rock solid timing, and 
(essentially) guaranteed delivery. It is no functionally no different 
from an analogue line. In fact, every analogue line feeds into an ISDN 
type connection between exchanges (ISDN, SS7, etc. are functionally 
equivalent).

> Noone doubts, that ISDN is suitable to transport analog fax.
> Finally the PSTN is 99,9% digital (ISDN/SS7), even if some
> subscriber lines are still analog.
> (Ok, ISDN is a managed network, and thus very high quality.)
>
> Since there are more and more regions in the world, where internet
> connectivity quality approaches to ISDN quality, analog faxing
> over VoIP becomes reliable and hassle free.
>
> You should have 128kbit in both directions, better 256kbit,
> maybe some QoS build in your router (e.g. Linux's iproute2),
> and pingtimes below 20ms to the VoIP-provider (PSTN-gateway).
>
> DSL with fastpath or internet by TV cable does provide this
> standard imho and become more and more available.
>
>
> Thus we shouldn't discourage people generally of faxing, even
> if there are a lot of trouble reports.
>
> Who can count the success stories with (analog) fax over IP,
> which are not posted?
>
> As far as I see, there are more users faxing without observing
> quality differences to ISDN than users with problems with fax
> over VoIP.
>
> This is, what various partners of ours do report after having
> replaced BRI connections by VoIP in some small and middle sized
> companies.
>
>
> Roger.
>