Weird rings on Fax machines w/ VG224 MGCP

Unanswered Question
May 25th, 2007
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Just deployed several VG224s, each with a mix of analog phones and fax machines. The phones work fine, and the fax machines work fine for outbound. However, when the receive a call, something a little strange happens after they pick up on the first ring. I hear 8 low humming noises, which last about 15 seconds. The fax then starts the transmission.

The VG224s run IOS 12.4(7e) w/ MGCP. Fax pass-through is used on the gateways, and we run G.711u accross the board. Config is as follows:

ccm-manager redundant-host

ccm-manager mgcp

no ccm-manager fax protocol cisco

ccm-manager music-on-hold

ccm-manager config server

ccm-manager config


mgcp call-agent 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

The fax machines are Canon 2050P SuperG3

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johnnylingo Thu, 05/31/2007 - 22:46
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That's great information, but these are on VG224s and I've already configured pass-through with G.711. I'm starting to suspect it's a problem with ECM.


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