Incoming Fax messages are not received by the XPhone Server. It can be seen in the Fax2Mail logfile that the XPhone server evaluates incoming numbers immediately and does not wait for the PBX system to transfer the Fax number fully. This is the reason why no user can be found on the XPhone server.
We recommend to set a fix length for fax numbers on the PBX system (e.g. 99xxx, 99 plus three characters and NOT 99z). In that case the complete number will be transmitted to our services.
If that's not possible, set a new parameter in the XPhone server under SETTINGS -> UM -> FAX -> GENERAL in the ADVANCED SETTINGS:
Fax2Mail\CapiForceInfoEvents. Set the value to 1 and save the settings. The UM services have to be restarted now.