[Asterisk-Users] T.38 bounty

[Steve Underwood]

SIP and H.323 are signalling. They need to know how to signal the use of 
T.38, so they must be modified.

The T.38 spec defines a streaming protocol over UDP, equivalent to RTP. 
The latest version also allows the use of RTP. T.38 can also use a 
non-quite-streaming TCP transport.

T.38 also defines a codec like way to transport the FAX information as 
digital data (i.e. not sending the modem tones as digitised audio). 
However, unlike most codecs the two directions are not independent. T.38 
processing needs to incorporate much of a T.30 engine, and deal with the 
information in both directions.

Regards,
Steve


Matthew Boehm wrote:

>So..need to modify the chan_sip and chan_h323 to recognize the T38 audio?
>
>That makes it sound more like T38 is a codec like 711/729 rather than a
>protocol like SIP/H323; is that right?
>
>The feature page for the new Sipura-2100 says this:
>
>  "Fax - G.711 Pass-Through or Real Time Fax over IP via T.38"
>
>So is that actually read as "Real Time Fax over IP via T.38 using SIP"?
>
>This is where my confusion starts; I don't know if T38 is a protocol or a
>codec...
>
>-Matthew
>
>----- Original Message ----- 
>From: "Steve Underwood" <steveu at coppice.org>
>To: "Asterisk Users Mailing List - Non-Commercial Discussion"
><asterisk-users at lists.digium.com>
>Sent: Friday, February 04, 2005 8:41 AM
>Subject: Re: [Asterisk-Users] T.38 bounty
>
>
>  
>
>>Do we have a chan_rtp? T.38 is to FAX as RTP is to audio. In fact, the
>>latest T.38 spec. now at last does what the original should have done,
>>and specifies a T.38 over RTP option.
>>
>>chan_h323 and chan_sip need to be modified to accomodate T.38.
>>
>>Regards,
>>Steve
>>
>>
>>Matthew Boehm wrote:
>>
>>    
>>
>>>Since t38 is seperate from SIP, you basically need a chan_t38 right?
>>>
>>>-Matthew
>>>
>>>----- Original Message ----- 
>>>From: "Roy Sigurd Karlsbakk" <roy at karlsbakk.net>
>>>To: "Asterisk Users Mailing List - Non-Commercial Discussion"
>>><asterisk-users at lists.digium.com>
>>>Sent: Friday, February 04, 2005 7:45 AM
>>>Subject: [Asterisk-Users] T.38 bounty
>>>
>>>
>>>
>>>
>>>      
>>>
>>>>hi
>>>>
>>>>there are some comments here,
>>>>http://www.voip-info.org/tiki-index.php?page=Asterisk%20T.38%20Bounty,
>>>>that people that have earlier offered high bounties for T.38 in
>>>>asterisk. Please add up, so the one that one day manages to add good
>>>>T.38 support may get something back for it :)
>>>>
>>>>roy
>>>>
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>>>>
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