calling card

  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

See calling card in American Heritage Dictionary 4

noun
  1. An engraved card bearing one's full name. Also called visiting card.
  2. A distinguishing characteristic or behavior.
  3. See phone card.
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