How does music on hold work? For outside callers, during call transfers, etc?

Calls coming from outside the district will hear music on hold when you place that caller on hold.

Any Lync call that you place on hold internally will hear a beep along with a visual message stating that they have been placed on hold.

Optional Note: when you are in the process of transferring a caller, it may be best to put that call on hold so that the caller does not hear you press keys on the phone during this process.