Customer has UC320 with external MP3 player and 3.5 to 3.5 line cord. UC320 is set to play external music source and not interanal. Unit software at 2.2.2. GA. I have tested MP3 and it is working, 3.5 to 3.5 is in external MOH plug. I have changed MOH to internal, rebooted, changed back to external, rebooted, but problem stays. I had customer play MOH on phone and then go pull the MP3 and see if music stopped, it didnt. Any IDEAS???
Are the external callers connected via FXO ports or SIP Trunks? Sometime there are incompatabilities with SIP Providers related to Music on Hold.
You might want to open a Support Case so the UC320W configuration can be obtained and any syslog traces.
A quick test would be to make an extension to extension call then place the call on hold. This eliminates the SIP provider.
Make sure the volume on the MP3 player is turned up. If the signal isn't strong enough the UC320 will assume no music is coming from the music source and fail back to internal MoH.