calling card

American Heritage® Dictionary of the English Language, Fourth Edition

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

Wiktionary

1. n. A small printed card which identifies the bearer, traditionally presented for introduction when making a social visit to a home or when attending a formal social event or business meeting.
2. n. An attribute, object, or behavior which is distinctly characteristic of someone or something.
3. n. Excrement, especially of a domestic animal.
4. n. A prepaid card or credit card, usually electronically readable, used to pay the charges when making a telephone call.

WordNet 3.0

1. n. a card that is used instead of cash to make telephone calls
2. n. a printed or written greeting that is left to indicate that you have visited
3. n. a distinguishing characteristic or behavior