As I open a contact with multiple numbers, I would like to see how the call was outcomed. So if it was a fax number, Wrong number, DNC, or old owner .(EXAMPLE) I can see it. Sometimes its a cell or office. It will act as an outcome for reports but also a note/label. Also if the contact is reimported or if that EXAMPLE number is imported for another contact, maybe the system can flag.
Thanks for the detailed suggestion! 
You can use the Tags 
feature to label phone numbers (e.g., “Fax,” “Wrong Number,” “DNC”) for better visibility and reporting.
Learn more about Tags
Also, Duplicate management 
checks for existing numbers during contact creation or import and flags duplicates to avoid redundancy.
Avoiding Duplicates Guide