I have 2 fields called "local tele" and "non-geo telephone" for the phone field for cck

Of these 2 fields I want at least one to be mandatory when creating the node

1. so if a user doesn't enter either of the two, a "required field" error is rendered and node won't submit

2. If a user enters "local tele" then non-geo can be ignored and vice-versa

3. if user enters both fields, then both will appear on the node

thanks