[cisco-voip] Fwd: Cisco ATA Fax Confusion

Lelio Fulgenzi lelio at uoguelph.ca
Fri Jan 22 15:54:01 EST 2010


omg. 

--- 
Lelio Fulgenzi, B.A. 
Senior Analyst (CCS) * University of Guelph * Guelph, Ontario N1G 2W1 
(519) 824-4120 x56354 (519) 767-1060 FAX (JNHN) 
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 
"Bad grammar makes me [sic]" - Tshirt 


----- Original Message ----- 
From: "Ryan Ratliff" <rratliff at cisco.com> 
To: "Lelio Fulgenzi" <lelio at uoguelph.ca> 
Cc: cisco-voip at puck.nether.net, "Rhodium" <rhodium_uk at yahoo.co.uk> 
Sent: Friday, January 22, 2010 3:45:58 PM GMT -05:00 US/Canada Eastern 
Subject: Re: [cisco-voip] Fwd: Cisco ATA Fax Confusion 

Yes they mean very different things. 


Now that I re-read the documentation I'm starting to doubt if I wasn't confused in my last email. It helps to think of it in terms of modem passthrough and fax passthrough (with modem passthrough being NSE-based and fax passthrough being protocol-based). 



-Ryan 


On Jan 22, 2010, at 3:07 PM, Lelio Fulgenzi wrote: 


Are we seriously saying that when Cisco says "fax pass-through" and "fax passthrough" they mean different things? 

oh boy. 

--- 
Lelio Fulgenzi, B.A. 
Senior Analyst (CCS) * University of Guelph * Guelph, Ontario N1G 2W1 
(519) 824-4120 x56354 (519) 767-1060 FAX (JNHN) 
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 
"Bad grammar makes me [sic]" - Tshirt 


----- Original Message ----- 
From: "Ryan Ratliff" < rratliff at cisco.com > 
To: "Rhodium" < rhodium_uk at yahoo.co.uk > 
Cc: cisco-voip at puck.nether.net 
Sent: Friday, January 22, 2010 2:57:18 PM GMT -05:00 US/Canada Eastern 
Subject: Re: [cisco-voip] Fwd: Cisco ATA Fax Confusion 

The lack of hyphenation is because fax pass-through is modem passthrough, which is NSE based. This call is working because the ATA passes the fax tones on to the VG224 as NSEs and it recognizes them. 

If we look at your config: 
fax protocol t38 nse ls-redundancy 0 hs-redundancy 0 fallback pass-through g711ulaw 

This means upon detection of the fax-tones (call outbound from VG224 to ATA) the VG will attempt to switch to T38. The fallback pass-through means that if T38 fails it will send NSEs as well. This is the part that is compatible with the ATA. 

-Ryan 

On Jan 22, 2010, at 1:42 PM, Rhodium wrote: 

Hi Ryan, 

I am using the terms as per the Cisco Press book "Fax, Modem, and Text for IP Telephony" by David Hanes and Gonzalo Salgueiro. Excellent reference! 

I guess what is throwing me off is your lack of hyphenations in the terms pass-through and passthrough in your replies. I understand the following: 

fax pass-through - Protocol based fax transmission 
fax passthrough - NSE based fax transmission 

As regards what I am seeing, yeah but the configuration doesn't imply that as one is setup for T.38 relay with pass-through fall back and the ATA is obviously only passthrough so I guess only a debug will answer that question as I was wondering whether the VG was falling back to NSE based passthrough for some reason. 

To be honest, I wouldn't expect it to work at all so why I am asking this knowledgeable forum about it incase I missed something in the documentation. 


Thank you for your reply as well as to all the other contributors. 

Regards, 

Jason 





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