I thought I would followup on this. We have internally implemented a priority field where we add numeric values for ranked phone numbers. “0” is assumed to the the main or primary phone, and the rest are ranked after that. It’s more flexible than a simple boolean, and is useful for more than just phones.
One of the use cases where we use this is to rank service_at_location level contact info. Some of our clients will prioritize contact info from service records, while others prioritize contact info from location records. At this level of granularity, prioritization allows us to reflect which phones and schedules should be shown to end-users first.