[Asterisk-Users] Fax detection in voip channel

[usedcanon]

-----Original Message-----
From: Lee Howard [mailto:faxguy at howardsilvan.com]
Sent: 21 October 2004 23:20
To: Asterisk Users Mailing List - Non-Commercial Discussion
Cc: usedcanon
Subject: Re: [Asterisk-Users] Fax detection in voip channel


On 2004.10.21 14:49 usedcanon wrote:
> Hi All,
>
> Is it possible to detect an incomming fax just as it is possible with
> Answer
> on a Zap channel. If not do others find the possibility of this
> enhancement
> useful too?

Doing fax over SIP or IAX would be a frustrating effort, and a complete
waste of time, IMO.  See:

     http://www.opencall.org/faq/x47.html

If you don't believe me, go ahead and actually *try* to send/receive a
fax through a WAN/internet VoIP connection.  You'll probably get
tolerable results with SIP-fax on a LAN, but run it through a VoIP
provider over the internet, and you'll have a mess, even if the codec
is ULAW/ALAW

What you really want is a T.38 channel driver.

Lee.

I understand what you are saying however there are scenarios where fax over
voip works fine, I have tested (briefly) with spandsp and have done so
sucessfully.

as a sperate solutions we use mediatrix gateways very successfully for fax
transmision over IP, our IP network is private and does not touch the
internet so we can gaurantee (to some extent) bandwidth and quality.

A T.38 solution would be most desirable, no doubt, but is there one ? I
don't even see a mention of it anywhere.

Umar