Abstract: One variant from a large number of possible services and/or service combinations is made available to the customer via a dialogue of human-machine interaction: a variant which the customer needs to solve his/her problem or to comply with his/her service request. In the process, it is checked whether the customer has access to the terminal configuration required for this variant and verified that the customer's terminal configuration supports the service and/or service combination concerned. For the customer's access to the calling card service, cards of completely different types, personal phone card, prepaid card, “call home” card, etc., are admitted. The type of calling card defines the customer's access authorization to the various possible services and/or service combinations, as well as the manner of billing those services. The present invention is suited for increasing the degree of automation of the services offered by calling card providers.