| 摘要 |
<p>RESTRICTED ACCESS LINE CIRCUIT FOR A COMMUNICATIONS SYSTEM Secure or private branch exchange like telephone service is simulated in a communication system, generally accessible to the public or otherwise, through the use of service codes associated with calling and called parties to restrict network access to and from predetermined subscribers, A line circuit for coupling a subscriber apparatus with a communication system includes a first storage location for storing a predetermined service code associated with the subscriber apparatus and a second storage location for receiving a service code associated with a called or with a calling subscriber apparatus. After a normal call progress in the communications system establishes a communication path between calling and called line circuits, signals representing the predetermined service code are transmitted from at least one of the line circuits via the communication path. If a service code is received from the communication path it is registered in the second storage location, Thereafter the contents of the first and second storage locations are available for use in a determination as to whether or not the communication path is to be linked to the subscriber apparatus via the associated line circuit.</p> |
