Exchange control for telephone calls

摘要

Telephone calls from at least one calling subscriber to at least one second required subscriber are made by following steps via an exchange, which accepts the called subscriber to be paying for the call. Then the acquisition call is carried out with the first subscriber, who is required to answer relevant questions. Then a free sign is forwarded to the first subscriber when he has correctly answered the asked question and the telephone number of the second subscriber is accepted from the first subscriber. The second subscriber number is dialled and the telephone connection is built-up.