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T38 rejected by ccm

Hi guys,

We did an upgrade from CUCM version: 7.1.5.34079-1 to CUCM version: 9.1.1.20000-5.

The problem now is that 95% of the incomming faxes are not coming into the fax server. (Some faxes are reveived)

Setup:

pri -> gateway (MGCP) -> CUCM -> ICT -> fax server

In de CUCM logs we see the next:

2 MDCX messages being sent to the gateway. The second one was being ignored.

This was because BOTH MDCX requests were in a=sendrecv mode. However, in the first MDCX, there is NO codec mentioned, while in the second there is.We believe this may be the reason for the MGCPInterface() not doing anything later in the call.

Did someone already had the same issue or knows a solution for the issue that i'm facing?

Any help would be much appreciated.

Regards,

Laurent

5 REPLIES

T38 rejected by ccm

First of all, ICT is designed to communicate different CCM clusters, not to a Fax Server. Change the ICT to a H323 Trunk (Gateway):

http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/srnd/7x/trunks.html#wp1044685

Then you can further troubleshoot.

--
Jorge Armijo

Please remember to rate helpful responses and identify helpful or correct answers.

-- Jorge Armijo Please remember to rate helpful responses and identify helpful or correct answers.

T38 rejected by ccm

Jorge,

This is correct.

However, This is a setup for 2007. According to Cisco back in 2007 we had to use the ICT in order for the faxserver to be able to do T.38 with MGCP gateways.

We only had to modify some timers in the call manager:

Media Exchange Interface Capability Timer ---> from 8 to 16

Media Exchange Timer --> from 12 to 20

Laurent

T38 rejected by ccm

Did you capture detailed traces for the failing fax call?

--
Jorge Armijo

Please remember to rate helpful responses and identify helpful or correct answers.

-- Jorge Armijo Please remember to rate helpful responses and identify helpful or correct answers.

T38 rejected by ccm

Jorge,

Yes I took detailed cm logs of a working fax and a rejected fax flow. Cisco confirmed that this is a bug in the call manager. They are working on a fix now.

Thanks

New Member

T38 rejected by ccm

Hi Laurent,

 

can I ask you what fax solution you use?

Because in case of our product we use SIP protocol to negotiate the call and maybe it could be helpful in your environment. Moreover, I think it is more user-friendly than ICT.

 

If so, just follow the link: http://www.2ring.com/netfax

 

Regards,

Martin

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