A contact is a person that a Sim has interacted with at least once, and who has thus been added to the Sim's relationship panel. The interaction can be as brief and casual as greeting a Sim, accepting a delivery, or making a purchase. A contact can be reached by use of the telephone. Special NPCs such as the Grim Reaper will not appear in the relationship panel.
In The Sims 2: Nightlife, contacts can also be Downtownies who have "heard" of the Sim from a mutual friend. This type of contact will have a blue overlay in the relationship panel, which works in much the same way as the fury overlay, and the relationship between the Sim and the Downtownie is given a boost for a short period of time. In Nightlife, both types of contact may phone asking to go downtown on an outing or date. Contacts are counted as friends for a short period of time even if the daily relationship is below 50.