RingCentral ships built-in hold music that admins can pick from or replace with their own WAV/MP3. Users describe the stock options as light instrumental “elevator” music. That’s anecdotal, and there’s no official track list we could find.
RingCentral
RingCentral hold music is built-in stock instrumentals that admins can pick or replace with their own WAV or MP3. See what users say they sound like.

MakerRingCentral
What callers hearStock instrumental 'elevator' music
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