Panasonic NS1000 Manual page 236

4.5 MOH/BGM Assignment
Via System Programming, the appropriate MOH/BGM source can be selected.
(For details of External MOH Sources, refer to the Installation Manual)
PBX Configuration -> 2. System ->
2. Operator and BGM
Select the source for BGM1, MOH and Transfer here
NB: User Defined MOH/BGM will not be heard when an IP Extension puts another IP
Click 'OK'
Extension on hold. The IP Extension will generate their own HOLD Tone.
(Any P2P communication (No DSP) will not hear User defined MOH)