In particular, in my "Phone" column (B), I am wanting to be able tell
by looking at the value in the cell, that another cell in the column
has the same value (the same phone number). Conditional formatting I'm
guessing is the tool (I still want rows who's values aren't duplicates
to be visible, so I would prefer not using a filter) - but what would
the formula be - I am lost on this one.

Thanks in advance for you help!

magmike