Way to mark record as main?

I would use acts_as_list and add a method to return the phone at
position 0 (or 1, depending on if acts_as_list is zero or one based).
Maybe call the method main_phone.

Now to make a phone number the "main" one just set it position to 1
using acts_as_list methods.

Oops. Sorry mixing my zero one based. I mean set it to position 0 of
acts_as_list is zero based.

vpim might help out…

A bit more specific:

parent.children[2].move_to_top

and it is zero based by the way.