Hi, so I just wanted to post a follow-up on this. I believe that we have faxing working now. Here are the settings that we did (the parameter on the EdgeGroup was the piece I was missing):
ON FXS GATEWAY
1.) Open 'SIP General Parameters' (Configuration|Protocol Configuration|Protocol Definition|SIP General Parameters)
a. Fax Signaling Method = G.711 Transport
b. Detect Fax on Answer Tone = Initiate T.38 on Preamble
2.) Open 'Fax/Modem/CID Settings' (Configuration|Media Settings|Fax/Modem/CID Settings).
a. Fax Transport Mode = RelayEnable
b. V.21 Modem Transport Type = Disable
c. V.22 Modem Transport Type = Disable
d. V.23 Modem Transport Type = Disable
e. V.32 Modem Transport Type = Disable
f. V.34 Modem Transport Type = Disable
g. Fax Relay Enhanced Redundancy Depth = 2
h. Fax Relay ECM Mode = Disable
i. Fax CNG Mode = Disable
j. CNG Detector Mode = Disable
On the Edge Group in GenesysCloud:
Changed the interedge codec to be G.711 instead of the default Opus. This would prevent the fax call from being transcoded and introducing additional loss that could impact the signaling. This can be done by adding this custom parameter
Property Name: trunk_media_codec
Data Type: List
Value: "audio/pcmu"