Fax problems with CCME and VG224

Unanswered Question
Jul 15th, 2009
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Dear all,

We have deployed a CCME on one of our subsidiaries attached to our Gatekeeper in Headquarters. Everything is working fine except one fax situation :

Internal dial-plan Headquarters --> to --> subsidiary KO (fax are not working)

Internal dial-plan subsidiary --> to --> Headquarters OK (fax are working)

Public dial-plan subsidiary --> to --> any public or international numbers OK (fax are working)

Public dial-plan Headquarters --> to --> subsidiary via international numbers OK (fax are working)

Fax are connected to a VG224 controlled with SCCP by the CCME

Here is the dial-peer configured on the Gatekeeper :

dial-peer voice 190 voip

description To Subsidiary

destination-pattern 60395....

progress_ind setup enable 3

modem passthrough nse codec g711alaw

session target ras

dtmf-relay cisco-rtp h245-signal

codec g729r8 bytes 40

fax nsf 000000

fax protocol t38 ls-redundancy 0 hs-redundancy 0 fallback cisco

no vad

Here is the dial-per used on the CCME of subsidiary :

voice service voip

qsig decode

allow-connections h323 to h323

allow-connections h323 to sip

allow-connections sip to h323

allow-connections sip to sip

supplementary-service h450.12


call start slow


dial-peer voice 201 voip

modem passthrough nse codec g711alaw

incoming called-number .

dtmf-relay h245-alphanumeric

no vad

I can give you results of debug or something else.

Thanks a lot for your help.


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Nicholas Matthews Wed, 07/15/2009 - 06:07
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Hi Florian,

Try adding this to your subsidiary site:

dial-peer voice 201

fax protocol t38 fallback cisco


flabarriere Wed, 07/15/2009 - 06:58
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Hi Nick,

I added the command "fax protocol t38 fallback cisco" into the CCME dial-peer but the problem is still there.



Nicholas Matthews Wed, 07/15/2009 - 07:02
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Hi Florian,

You may have another problem that I can't analyze from the information given.

First check that the call is switching over in 'show call active voice brief'. You should see the codec as t38. You can also use 'show voice call summary'. If so, check for line slips 'show controllers t1' and packet loss in show call active voice brief. You would need to check the entire call flow, because so far you've only informed of GK--CME--Fax machine. No idea what is to the left of the GK.


flabarriere Wed, 07/15/2009 - 23:46
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Hi Nick,

The call seems to be well established between the 2 faxes because the subsidiary fax is "ringing" when we send a document from headquarters (our fax number in HQ is 7386752).

Behind our Gatekeeper we have a CUCM cluster and Nortell, Alcatel PBX.

Please find attached the results of commands needed.

The codec used is g729, maybe this is why they can't established the connection.

Thanks for your help,


Nicholas Matthews Thu, 07/16/2009 - 05:52
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Try adding this to both routers:

voice service voip

fax protocol t38 fallback none

As well, if you're on 12.4(15)T-T8, upgrade to T9 as there is a bug in those versions regarding switching over.



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