Fax tranmissions keep failing

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Dec 21st, 2007
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I have problems sending outbound faxes between a SG3 capable fax machine when attached to vg224 gateway.

I have 15 fax machines all attached to an MGCP enabled gateway which is controlled by CCM 4.2.3. I have an esker fax server that is IP enabled and communication between the fax machines and the server fail.

Currently there are no translations in call manager to route calls between the internal network and the esker fax server so all calls between the devices are routed via the pstn.

The fax machine routes the call through a VG224 gateway and then onto a Cisco 2821 H323 gateway. The call then comes back into the site via a different ISDN 30 into another Cisco 2821 H323 gateway. On the inbound h323 gateway is a dial-peer that routes all faxes to the IP side of the Esker server.

When using the vg224 as the analogue gateway a fax will error out. This means Esker sends me via email only part of the document. The fax machine will then start re-sending and eventually send me the remaning documnet (a 4 page fax sometimes means 4 seperate emails with 1 page in each).

Now if I put the same fax machine onto a Cisco ATA and route the call the same way all works fine. As soon as I put the fax machine back onto the vg224 the fax fails as described. The fax machine is a Sg3 capable device and I know an ATA only communicates at 14.4 so I believe this a speed issue but not sure where, as the fax machines can send documents to other fax machines fine, just not the esker fax server.

I have looked and I think i need to configure SG3-g3 fax relay but the commands don't exist.

The vg224 and gateways are setup for t38 fax relay. I'm unable to use the command fax-relay sg3-g3 as it doesn't exists in global or dial-peer levels.

I'm running IOS version.

vg224 = vg224-i6k9s-mz.124-16.bin

2821 = c2800nm-ipvoicek9-mz.124-16.bin

If anyone can help I would be most grateful, I hope my issue makes sense.


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Overall Rating: 3.5 (2 ratings)
dgahm Fri, 12/21/2007 - 08:18
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What usually happens is that Super G3 (which use V34 modem 33.6) machines work when talking to G3 machines (they negotiate and use G3 14.4) and fail to other Super G3. One solution would be to disable SG3 on all fax machines. Some allow you to do this explicitly, on some you can disable ECM which is required for SG3.

Please rate helpful posts.


martin.chapman44 Mon, 12/24/2007 - 01:59
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Is there anyway to enable something on the VG224 to set this?

I only ask, as when attached to an ATA the faxes work fine without any chnages to the fax machines.

Also the problem is only when sending faxes to the fax server and external faxing is fine. I have looked at the ECM function and when I disable this the baud rate is dropped to 9600 on the fax machines. This is a bit slow for sending faxes.




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