We have a SIP trunk going from our CUCM to a SIP provider, the faxes are being sent right but we cannot receive faxes.
Capturing traffic I see that the provider sends some INVITE messages correctly, but in the last one always the CUCM answers with a 488 message "Not acceptable Media" as you can see in the attachment.
Is there anything that I can change in the configuration to avoid this problem? I thought that T.38 would work by default on a SIP trunk.
Any help will be appreciated.
Thanks in advance