[asterisk-biz] Faxing with Asterisk

[Sam Tam]

Elastix is reasonably good at doing fax again as suggested by Bret, Jitter
and packet loss is going to hurt your fax. 
High latency is not a problem but constant changes of latency will be and if
your network has latency problem then I would not waste time. We have a
solution setup in datacenter with the T1 connected directly next to the
Elastix box. And it works like Magic. 
However doing it in China, we have nothing but all bad luck..
So m
SAm

-----Original Message-----
From: asterisk-biz-bounces at lists.digium.com
[mailto:asterisk-biz-bounces at lists.digium.com] On Behalf Of Trixter aka Bret
McDanel
Sent: Tuesday, February 03, 2009 2:41 AM
To: Commercial and Business-Oriented Asterisk Discussion
Subject: Re: [asterisk-biz] Faxing with Asterisk

On Mon, 2009-02-02 at 10:14 -0800, deva free wrote:
> Hello
> 
> Is it possible to have a commercial grade fax over ip solution with
> Asterisk? for a fax-email /email-fax business.
> 
> 
That depends.  Jitter and loss are the killers of this, not really
latency.  If latency was the issue (and I have seen many suggest that it
is) then you wouldnt be able to fax with TDM from say NY to Africa,
Russia or many other places that faxes routinely go through to.  As a
result you have to ensure that the bandwidth between you and the
provider is good, and this can be really problematic if you have any
tertiary providers between yours and theirs.  T.38 can help to some
degree with this but its not a magic bullet, and its my understanding
that the spec is vague (gee just like sip, rtp, rfc2833 and a few
others) and so providers tend to do it differently forcing their own
interpretation of the T.38 spec, or just inventing their own blatently
wrong implementations.

As for commercial I do not know what you mean by that, there is the
reception of the data, but odds are there is a conversion process to
change it from a G3 tiff to say a pdf, and other things, and normal
scaling rules apply.  In addition, you have issues of what features the
faxes in question support, faxes support a variety of features and they
negotiate at the start up what each side supports and generally try to
use the "best" common feature set, but if you need something in
particular you may lose that feature if its not supported.  Further,
spandsp afaik is still GPL and so the GPL rules apply (ie you cant
distribute a system with asterisk that is not GPL, for example the
Asterisk Business Edition).  Spandsp only matters if you are looking for
a "software only" solution and not some hardware based one.  There are
work arounds that can be used to have a mix of gpl and non-gpl software,
for example iaxmodem builds a "license condom" by using a socket to get
the data from asterisk and send it elsewhere for processing.

Further J2 has a patent on certain aspects of a fax->email solution, you
may have to pay them a licensing fee if you do this.  



> 
-- 
Trixter http://www.0xdecafbad.com     Bret McDanel
pgp key: http://pgp.mit.edu:11371/pks/lookup?op=get&search=0x8AE5C721