The KX-TDA 50 doesn't appear to be able to do Music-On-Hold, but Background Music only.
The KX-TDA 100/200 have two ports for Music-On-Hold:
- MOH1: External Music Source Port
- MOH2: Selectable Internal/External Music Source port
Program 710 to select the Background Music Source, then use Program 711 and Program 712 for music on calls being transferred.
Let us know!