calling card

noun

1. a small card with one's name, and sometimes one's address, on it, used in making visits
2. Informal an identifying mark or characteristic left by someone or something his calling card was a string of home runs
3. a form of credit card used for making long-distance telephone calls, by means of which the charges may be either applied to a home or business account or (often phone card) deducted from a prepaid amount