[cisco-voip] SG3 Faxing and IOS v15.1 (new thread)

[Nick Matthews]

The feature is a DSP-software feature in 15.1(1)T.  This means it should not
be protocol dependent.  And though it is a DSP feature, it is still not
hardware dependent (per our last thread).

To my recollection, you should be able to use fax-passthrough with G711 with
CUCM.  I seem to remember doing this many times, but the only scenario I
can't remember if it works correctly is G729->G711 switchover with CUCM with
passthrough.

The modem passthrough recommendation may be based in the pre-SG3 era, and
not be updated in the document.  The cisco.com fax documents aren't
particularly great sometimes.  I will be interested to see whether or not
the SG3 makes T38 more stable.  My thought it yes, and I would personally
start using T38 as my default rather than modem passthrough with this new
feature.

Modem passthrough pseudo-supported SG3 before.  Sometimes it would work,
sometimes not, because the DSPs were incapable of promising SG3 speeds.
That should also be changed now, as they support 56k speeds.

-nick



On Fri, Apr 9, 2010 at 9:54 AM, Lelio Fulgenzi <lelio at uoguelph.ca> wrote:

> I thought I'd start a new thread to help with future searches.
>
> I took a closer look at that link I sent out earlier, the one that pointed
> me to CUBE configuration, and it turns out there is a section in there that
> talks about:
>
> ------------------------------
> SG3 Fax Support on Cisco TDM-IP Voice Gateways and Cisco UBE Platforms
>
>
> http://www.cisco.com/en/US/docs/ios/voice/cube/configuration/guide/vb-gw-config.html#wp1423706
> ------------------------------
>
> While it goes in depth about relay, for fax pass-through, it simply points
> to an old v12.4T document (link<http://www.cisco.com/en/US/docs/ios/voice/fax/configuration/guide/vf_cfg_fx_passthr_ps6441_TSD_Products_Configuration_Guide_Chapter.html>).
> The new one<http://www.cisco.com/en/US/docs/ios/voice/fax/configuration/guide/vf_cfg_fx_passthr_ps10592_TSD_Products_Configuration_Guide_Chapter.html>(for v15.1) doesn't seem to go into any specific discussion about SG3
> speeds, in fact, all it talks about is SG3 downgrading to G3.
>
> In reading it more closely, it mentions only: MGCP, H323, and SIP. Is SCCP
> out?
>
> In reading it even more closely, it mentions that if you're using all Cisco
> gateways, you should use modem passthrough.
>
> *Note *Modem pass-through is preferred if all of the involved gateways are
> Cisco IOS gateways.
>
> And even more reading says if you're using CCM, you MUST use modem
> passthrough.
>
> *Note *If you need to configure fax pass-through to work with Cisco
> CallManager (CCM), you must use the *modem passthrough nse* command. The f
> *ax protocol pass-through *command does not work with CCM, which relies on
> NSE information.
>
> So what's the deal?
>
>    - Is SG3 supported on modem passthrough which I now must use?
>    - Does that mean I can stick with SCCP on my VG224, since SCCP supports
>    modem passthrough?
>
>
>
>
>
>
>
>
>
>
> keywords: super G3 faxing fas passthrough fax pass-through confusing
>
> ---
> Lelio Fulgenzi, B.A.
> Senior Analyst (CCS) * University of Guelph * Guelph, Ontario N1G 2W1
> (519) 824-4120 x56354 (519) 767-1060 FAX (JNHN)
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> Cooking with unix is easy. You just sed it and forget it.
>                               - LFJ (with apologies to Mr. Popeil)
>
>
> _______________________________________________
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> https://puck.nether.net/mailman/listinfo/cisco-voip
>
>
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