Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.


Weird rings on Fax machines w/ VG224 MGCP

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


Re: Weird rings on Fax machines w/ VG224 MGCP

The Cisco fax relay protocol supports only G3 fax and not SuperG3. SuperG3 calls appear to the VG248 as a modem call rather than a fax call.

SuperG3 fax calls should always succeed, but take place in pass through mode rather than in Cisco fax relay.


Re: Weird rings on Fax machines w/ VG224 MGCP

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.