| 摘要 |
PURPOSE: A method for blocking the channel of an ISDN(Integrated Services Digital Network) subscriber of PRI(Primary Rate Interface) is provided to increase a call success rate of the subscriber by selecting only normal channels to the exclusion of abnormal channels. CONSTITUTION: When a call is terminated in a private branch exchange via a national branch exchange(200), the ISDN subscriber software of an ISDN subscriber unit selects the channel of the corresponding subscriber(202). In response to the channel selection, the channel block information of a database is checked(204). If the channel block information is not in the database, an idle channel is selected(206). If the channel block information is in the database, the channel block information is read(212) and the blocked channel is excluded from the channel selection(214).
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