In version 7.94 and higher:
Please note that Phone Sharing functionality is no longer present in The Raiser’s Edge software beginning with version 7.94, and higher.
In version 7.93 and earlier versions:
If a phone type is marked as Do Not Share in Configuration, it cannot be shared with any other records, even the relationship record of the constituent. Therefore, when this address is shared with another, the phone number is left off.

If an address is shared and the phone type is sharable, it will show on all shared records. When the phone type is marked as Do Not Share, it is not removed from shared records, but then shows as Cannot Be Shared.