CM: Outbound fax calls not working over public SIP trunks. Denial Event 2378 seen.

Doc ID		SOLN231658
Version:		4.0
Status:		Published
Published date:		21 Mar 2018
Created Date:		25 Jun 2013

Author:

Max Barker

Details

CM: Outbound fax calls not working over public SIP trunks. (CM-->SM-->Acme SBC -->Sprint)

Customer would make outbound fax call from analog port in a MG. In list trace you can see CM 'reject' the T38 request from the SP with a '488 Not Acceptable Here' and print denial event 2378 as per below:

2378 RejReqT38-not in rgn/hw 7F4003AE F2

Problem Clarification

CM: Outbound fax calls not working over public SIP trunks. (CM-->SM-->Acme SBC -->Sprint)
If the FAX machine is a 3rd party device like MP112 AudioCdes, please make sure that device is also configured for T.38 enabled.

Cause

't38-standard' not enabled on page 2 of the ip codec set.

Solution

Enable t38-standard on page 2 of the corresponding ip-codec-set form as per below......

display ip-codec-set x Page 2 of 2

IP Codec Set

Allow Direct-IP Multimedia? n

                          Mode                         Redundancy
FAX                    t.38-standard            0 <<<------------------Enable t38-standard.
Modem               off                             0
TDD/TTY           US                             3
Clear-channel     n                               0

In another case inbound and outbound fax calls were not working over T.38. Carrier made changes to allow the fax over SIP to work properly.

Additional Relevant Phrases

Denial 2378, Deny inbound request. T38 not supported in rgn/hw intersection. Some faxes are not going through as CM and far end cannot negotiate T38 codec Fax calls are failing as CM and far end cannot negotiate T38 codec.

Avaya -- Proprietary. Use pursuant to the terms of your signed agreement or Avaya policy