[cisco-voip] On net faxing?

[Wes Sisk]

Yes,

Modems use a different set of tones from fax machines.

/Wes

> -----Original Message-----
> From: Voll, Scott [mailto:Scott.Voll at wesd.org]
> Sent: Tuesday, March 02, 2004 10:59 AM
> To: Wes Sisk; cisco-voip at puck.nether.net
> Subject: RE: [cisco-voip] On net faxing?
> 
> 
> Is there any difference between Modem Pass through and fax pass through?
> It looks like my MGCP GWs only do Modem pass through and my h323 gw is
> IOS 12.2.11T so it only does Modem pass through also.
> 
> TIA
> Scott
> 
> -----Original Message-----
> From: Wes Sisk [mailto:wsisk at cisco.com] 
> Sent: Tuesday, March 02, 2004 5:32 AM
> To: Voll, Scott; cisco-voip at puck.nether.net
> Subject: RE: [cisco-voip] On net faxing?
> 
> [resending w/o the attachment b/c moderators limit us to 40kB, will
> unicast
> you the attachment]
> 
> Scott,
> 
> > I need help understanding how to make it work and how it actually
> works.
> > Two MGCP Gateways one H323 and CM 3.3.3sr4.
> >
> > 3 scenarios
> >
> > 1. Fax comes in from the PSTN hits Voice GW where it is set to G711 by
> > Fax Pass- Through.  Then it's routed to a different region.  I think I
> > understand this.  The gateway makes it a G711 Call even though it's
> > going across a WAN.
> 
> ws: I will infer you mean a different region in CCM that should cause a
> g729
> call.  The call does get extended from ogw to tgw as a g729 call, but
> when
> the first fax tone is detected the gw's use "upspeed" so CCM still
> believes
> it is only a g729 stream, but the gateways change the in-use codec mid
> stream.
> 
> > 2. On Net Faxing.  Two ATA186's, one at central site, one at the
> remote
> > site, need to fax from one to the other.  Really this never goes
> through
> > a Voice Gateway.  Yes it may hit one for routing IP but really doesn't
> > hit it for Voice purposes.  Does CM take care of it?  How would CM
> know
> > what to do with it?
> 
> ws: The upspeed functions must be performed by the ATA's.  The fax
> upspeed
> functionality is discussed here:
> http://www.cisco.com/en/US/partner/products/hw/gatecont/ps514/products_a
> dmin
> istration_guide_chapter09186a00801e0dff.html
> 
> (or attached)
> 
> > 3. now I have a remote ATA that is going to fax out the central site.
> > The only v-gateway it hits is the gateway to the PSTN at the central
> > site.  So it has already gone across the WAN.  Now what?
> 
> ws: same deal as #2, the ogw and tgw start the call as 729 but when they
> recognize fax tones they must upspeed.  This is done without any
> notification to CCM, and at this point your WAN bandwith utilization as
> reported by your CCM locations feature will be incorrect.
> 
> HTH.
> /Wes
>