[asterisk-users] T.38 Faxing and Asterisk

[Paul Bryson]

I understand that Asterisk 1.4 should support T.38 pass-through, but I 
need Asterisk (or something on the Asterisk box) to act as a T.38 
endpoint.  Judging from the unclaimed $12,000USD bounty, it doesn't 
appear that Asterisk itself can do this.
http://www.voip-info.org/wiki-Asterisk+T.38+Bounty

Does anyone have any experience with this, or are able to point to an 
example of this working?

It looks like I need something along the lines of Asterisk detecting an 
incoming fax, passing it to IAXmodem (or something, I don't know what 
could do it) for conversion to T.38, and then the T.38 getting passed on 
to an appropriate T.38 supporting ATA (or other endpoint).

Or at least I think that's what we need to support these scenarios.

Scenario 1:
1. Somebody sends us a fax, and is an analog signal until it gets into 
the Telco's network where it is translated to digital audio.
2. The call comes in over our T1 to our Asterisk box.
3. Asterisk box answers and converts the incoming digital audio fax into 
T.38 data.
4. Asterisk box contacts an ATA that supports T.38 (such as the 
Grandstream HT502) and sends it the T.38 data.
5. The ATA converts the T.38 data into an analog fax signal for an 
attached fax machine.

Scenario 2:
1. Somebody sends us a fax, and is an analog signal until it gets into 
the Telco's network where it is translated to digital audio.
2. The call comes in over our T1 to our Asterisk box#1.
3. Asterisk box#1 answers and converts the incoming digital audio fax 
into T.38 data.
4. Asterisk box#1 sends Asterisk box#2 the T.38 data over a relatively 
slow/high latency connection.
5. Asterisk box#2 contacts an ATA that supports T.38 and sends it the 
T.38 data.
6. The ATA converts the T.38 data into an analog fax signal for an 
attached fax machine.

Scenario 3:
1. Our fax machine sends a fax out over an analog line attached to an 
ATA that supports T.38.
2. The ATA converts the fax over analog signal to T.38 data.
3. The ATA sends the T.38 data to Asterisk box.
4. Asterisk box converts the T.38 to fax over analog and sends the 
digital audio out over the T1.
5. At the other end of the Telco's network the digital audio is 
converted to analog and a fax machine receives the fax.

Scenario 4:
1. Somebody sends us a fax, and is an analog signal until it gets into 
the Telco's network where it is translated to digital audio.
2. The call comes in over our T1 to our Asterisk box.
3. Asterisk box answers and converts the incoming digital audio fax into 
T.38 data.
4. Asterisk box contacts a system running sipX with a SIP over UDP 
connection and sends it the T.38 data.
5. sipX contacts an Exchange 2007 Unified Messaging box and sends it the 
T.38 data.
6. Exchange 2007 converts the T.38 data to an image in an email and 
stores it in the user's inbox within Exchange.


Paul Bryson