I have both RingCentral and Google Calendar (we use G-suite) installed in my Android Work Profile (using Android 8, Samsung S8).
When I click a phone number in Google Calendar, it automatically dials via RingCentral. Other apps launch my default phone dialer. I have cleared all default apps from Calendar and RingCentral, but can't seem to prevent this behavior.
I would prefer that my standard Phone dialer is used for all phone numbers from within the Work Profile.