Fax connection issue VG224 MGCP CCM 7.0

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Mar 30th, 2009
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I am having issues with sending faxes to certain remote fax machines via local fax machines connected to our VG224 Analog gateway. The fax machine reports poor line quality and the faxes don't go through. If I go to another fax machine connected straight to the PSTN faxes to the same number go right through. I'm thinking this is something to do with my VG224 or CCM configuration. The path of communication is as follows:


My MGCP Config for the VG224 is listed below, any thoughts would be appreciated.

ccm-manager redundant-host 172.16.x.x

ccm-manager mgcp

ccm-manager music-on-hold

ccm-manager config server 172.16.x.x 172.16.x.x

ccm-manager config



mgcp call-agent 172.16.x.x 2427 service-type mgcp version 0.1

mgcp dtmf-relay voip codec all mode out-of-band

mgcp rtp unreachable timeout 1000 action notify

mgcp modem passthrough voip mode nse

mgcp package-capability rtp-package

no mgcp package-capability res-package

mgcp package-capability sst-package

no mgcp package-capability fxr-package

no mgcp timer receive-rtcp

mgcp sdp simple

mgcp fax t38 inhibit

mgcp rtp payload-type g726r16 static


mgcp profile default

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Nicholas Matthews Mon, 03/30/2009 - 11:28
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A couple of things to try:

no mgcp fax-relay sg3

no mgcp fax-relay ans

As well, on your PSTN gateway:

voice-port 0/0/0:23

input gain 9


no shut

There's a bug out there for low-volume fax tone detection, and this may help you work around it.

The first couple of commands may be related to SG3 faxes failing.


NPT_2 Mon, 03/30/2009 - 11:59
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Am I supposed to use the

no mgcp fax-relay sg3

no mgcp fax-relay ans

commands on the vg224? I'm running 12.42T5 Code on the vg224 and it doesn't recognize those commands. I'll try the input gain commands shortly.

Nicholas Matthews Mon, 03/30/2009 - 12:39
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If you're on an IOS version that doesn't support those commands there's no problems. But, they would still need to be applied to the PSTN gateway if it will take them.


webberr Wed, 04/01/2009 - 10:20
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You might want to try the commands:

mgcp package-capability fxr-package

mgcp default-package fxr-package

We had a 2811 with FXS ports and that solved our problem. Just an idea...


jdelgad2 Thu, 02/02/2012 - 12:33
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I had a similar problem and found this Bug CSCtu18634, you can check the details on it to see if it works.


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