A calling card is a generic term for a credit card issued by a telephone company and used for charging local and long distance calls. Calling card information is data supplied during the progress of a call. Typically, the information required varies with the different dialing procedures required by the various calling cards.
An application provides TAPI with the information it needs to display a dialog box, from which the user can choose a calling card. (The calling card numbered 0 means "use the default dialing rules for the country you are in.") The routine returns, among other information, the user's location (country and area code), the number of calling cards registered for this user in the registry, and the preferred calling card for that location. This calling card information is applied by the lineTranslateAddress function and does not happen automatically through lineMakeCall.
Typically, an application would prepare a menu choice for the user, such as whether to make a call with the default carrier, to override the default carrier and use a given calling code, or simply to use another specific dialing sequence.