[cisco-voip] On net faxing?

[Wes Sisk]

[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