Mailing List Archive

[.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_admin
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

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@cisco.com]
Sent: Tuesday, March 02, 2004 5:32 AM
To: Voll, Scott; cisco-voip@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

Yes,

Modems use a different set of tones from fax machines.

/Wes

> -----Original Message-----
> From: Voll, Scott [mailto:Scott.Voll@wesd.org]
> Sent: Tuesday, March 02, 2004 10:59 AM
> To: Wes Sisk; cisco-voip@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@cisco.com]
> Sent: Tuesday, March 02, 2004 5:32 AM
> To: Voll, Scott; cisco-voip@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
>