[cisco-voip] Fax and Modem Parameters ?

[Ed Leatherman]

FWIW, Here is how we program our VG248 fax ports when we run into
issues.. have had fairly good success:

global telephony settings:
Passthrough Signaling : IOS Mode
Passthrough Codec: G.711 u-law

Port specific settings:
Call Control mode = Basic
Caller ID = Disabled
MWI Method = none
Fax Relay = Disabled

CCM Admin port settings, basically make sure to match the port config on the VG.
Call Control Mode = Basic
Caller ID = Disabled
MWI = none
Fax Relay = disabled

We don't have any CMM blades, only thing I can comment on is make sure
clocking is correctly configured for your T1 ports, clock slip errors
kill faxes. Could be issue on the network too, one time we had a PIX
that was delaying packets every 20 seconds, basically killed any fax
traffic going thru it. Took us an embarrassing amount of time to track
it down (with help from TAC).

Pass-through is definitely what you want to use assuming the call is G.711.

Hope that helps,
Ed

On Wed, Feb 18, 2009 at 9:27 AM, Dane <dane at pktloss.net> wrote:
>
> I have been getting reports of faxing issues since we moved to some
> new circuits.  Faxes are connected to VG248s, new circuits are
> connected to WS-SVC-CMM-6T1 and old circuits were connected to same
> 6509 but the port was on a 6608.
>
> I noticed that on the 6608 ports you have the section for "Fax and
> Modem Parameters" however on the CMM-6T1 the ports don't have anything
> related to faxing in there.
>
> On the CMM-6T1 module config there is one item related to Fax mode
> that can be either Fax Passthrough or Fax Relay.  Currently Fax
> Passthrough is selected.
>
> The fax machines are giving an error "poor line condition" or "busy no
> response", however there is really no consistency in the user reported
> errors.  Sometimes it works, sometimes it doesn't.  Different numbers
> being called, different fax machines reporting the issues.  I do know
> that this was not an issue prior to moving the circuits, so my guess
> is its the new circuits or simply related to the fact I am using these
> CMM-6T1's now as opposed to the 6608.
>
> I read about making sure the ECM was off on the fax machines and that
> speed was set to 9600.
>
> Other than that anyone have any thoughts or suggestions on troubleshooting this?
>
> Thanks


--
Ed Leatherman
Assistant Director, Voice Services
West Virginia University
Telecommunications and Network Operations