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. Sims are likely to obtain this type of contact shortly after a high scoring outing or date. 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 while the blue overlay is there, even if the daily relationship is below 50. This can allow a Sim to get a promotion they otherwise wouldn't have gotten.