Fax Fails

Hi

I have an issue, the PABX Vendor only supports G711 pass through for fax, and the Service Provider Supports T.38 and G711, fax intermittently fails depending on where the fax is sent to or from, ie Analog Line , FOIP, Right Fax

I know i need to have transcoding but I am not sure if this is correct :

Codec Policy on the realm of the PABX

codec-policy

        name                                    STORES

        allow-codecs                            G729 PCMA

        add-codecs-on-egress                    G711FB

        order-codecs

        packetization-time                      20

        force-ptime                             disabled

        secure-dtmf-cancellation                disabled

        dtmf-in-audio                           disabled

        tone-detection

        tone-detect-renegotiate-timer           500

        reverse-fax-tone-detection-reinvite     disabled

        fax-single-m-line                       disabled

        evrc-tty-baudot-transcode               disabled

Codec Policy on the realm of the SP

codec-policy