On AS5350XM logging shows these two messages:
%SIP-3-BADPAIR: Unexpected event 20 (SIPSPI_EV_CC_CALL_FAX_PASSTHROUGH_START) in state 9 (STATE_DISCONNECTING) substate 0 (SUBSTATE_NONE)
%SIP-3-BADPAIR: Unexpected event 17 (SIPSPI_EV_CC_CALL_T38_FAX_START) in state 4 (STATE_RECD_PROCEEDING) substate 0 (SUBSTATE_NONE)
We are deploying one PBX with two E1 ports connected to AS, which has SIP trunk to service provider, and we experience some difficulties with fax transmission.
As you can see in att. - there are some errors on one E1 controller (E1 3/2) - I suppose that could be the reason for fax problems....