[asterisk-users] receive faxes

[Steve Underwood]

On 05/05/2011 03:29 AM, Lee Howard wrote:
> David Backeberg wrote:
>> On Wed, May 4, 2011 at 12:00 PM, A J Stiles
>> <asterisk_list at earthshod.co.uk> wrote:
>>> (For my part, I'm actually surprised that nobody came up with a proper
>>> protocol for encapsulating the stream of zeros and ones that make up 
>>> a fax
>>> transmission but rely on the precise timing inherent with a 
>>> circuit-switched
>>> network, into something more suitable for sending over a 
>>> packet-switched
>>> network.  That would have fixed it good and proper.)
>>
>> They did. It's called TCP / IP.
>>
>> It allows sending PDFs, and they can even be encrypted.
>>
>> Faxing is for people who haven't heard of the internet.
>
> Nobody has said that faxing couldn't use TCP/IP... and there's no 
> reason why T.38 couldn't use TCP/IP.  Nobody has said that faxing 
> couldn't use HTTP as a transport... or SSL... or any other kind of 
> sensible mechanism.  Why in the world people try to keep faxing (data 
> transfer) tied-down to audio channels by putting T.38 into H.323 or 
> UDP/IP SIP beats me.
T.38 is defined to work over TCP/IP (although not TLS for some reason), 
but its rarely used. It can only really work between 2 T.38 boxes 
directly connected to the data network. To interwork with analogue FAX 
machines you need to maintain fairly tight timing, and that means 
sticking with UDP, as it does with all the other streaming stuff we do 
over UDP.

Steve