When updating phone numbers in an import (following a OVM or Telemarketing effort) we want the ability to update the phone type to "bad phone number" (which we can) and then uncheck these as primary AND add an end date.
If you do this, the system will give you validation errors that state:
A primary number cannot have an end date
A constituent must have a primary phone
There are a lot of instances where a phone number that was on a constituent record is no longer valid.
If nothing else, allow the user to over-write this error by granting access to a "dismiss" option.