Fax cannot receive from PSTN

Unanswered Question
Apr 16th, 2007

Dear all,

I have a problem with fax in one of my site. I'm using MGCP for fax protocol. The faxes can send and receive faxes using extension. They also can send faxes through PSTN, but they cannot receive faxes from PSTN. This problem happens in only certain faxes (in this case Xerox Document Centre). I've tried to change the fax settings one by one, but it didn't give any positive results. Why this can happen ? Are there any certain types of fax that are not supported by Cisco ?

I have this problem too.
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Zin.Karzazi Mon, 04/16/2007 - 05:26

Ensure that the Gateway Calling Search Space include FAXs Partitions. Also activate some tracing to see what is exactly happening.

sr2290723 Thu, 04/26/2007 - 03:11

Well, I'm sure that the CSS has include Fax Partitions. Only several fax can communicate with this fax through PSTN. But when I take the fax line to bypass the VG, everthing is OK. I tried to enable trace in "error" level at the FXO and FXS port, but nothing results from the trace. What do you think ?

anwar-ahmed Thu, 04/26/2007 - 10:19


I am trying to configure FAX through FXS port in cisco 3845. FXS is configured through MGCP protocol, Tone is present.

Fax machine is not responding but silence.

Please advice

sr2290723 Thu, 04/26/2007 - 18:22

It means that the fax cannot either send or receive even internally? Have you tried to replace the fax with analog phone ?

Can you attach the configuration of your voice gateway and make sure that you have configured the CCM correctly (partition, CSS, route pattern, route group, route list)


anwar-ahmed Mon, 04/30/2007 - 15:00


I have configured cisco 2821 router with MGCP.

When I call to the phone connected to the FXS port from IP Phone, I can not hear any voice but other party can hear my voice.

I have to configure a fax to the fxs port.

My router configuration:





voice-port 0/0/0


voice-port 0/0/1


voice-port 0/0/2


voice-port 0/0/3




mgcp call-agent X.X.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

mgcp package-capability pre-package

no mgcp timer receive-rtcp

mgcp sdp simple

mgcp rtp payload-type g726r16 static


mgcp profile default



dial-peer voice 100 pots

application mgcpapp

port 0/0/0






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