Upon upgrading to LD 188.8.131.52 this afternoon External MOH does not play. System continually plays Internal MOH file even though "External" is selected via Config utility. I have attempted to switch it Internal, reboot, switch back to External, reboot, only to it still only play the Internal (vs External) source.
Thanks for download and installing the 2.2.3(5) firmware build. In my setup I am able to hear an external music source (also running 2.2.3(5)). Can you please try to increase the volume setting on your external device? If the UC320W does not detect an external source it defaults back to an internal source.