Aldert,
There are two packages for storing phone and address information generically. They are postal-address and telecom-number.
The contacts package is built on this.
If there is an actual "person" who is responsible for the phone and another for faxes for an event in your example, wouldn't you just link the first person as the phone contact and the second as the fax contact?
Postal-address and telecom-number don't have user interfaces. Mayeb what you imagine is a ui package to enter and link phone and address data, which could be used by a contact package as well as for your examples.
