Well, not quite. There could be multiple regional offices for "Organizations", with each one having their own unique set of phone numbers. Again, for the purposes of discussions, let's assume that abstracting to a higher level is not possible.

Or rather, if you want to assume that it is possible, that is fine too. You can proceed on the notion that you can abstract it up to 5 higher level objects which could own phone numbers.

The problem still remains as to how to create the "complex many to many" relationships of phone numbers to each of these 5 higher level objects.

G.