| 摘要 |
A terminal station at the receiving end transmits selection information to the exchange describing connections which can or cannot be set up. The selection information may comprise complete telephone numbers or, for example, national and/or local preselection code numbers only. The exchange switches through to the terminal station only those connections which can be set up according to the selection information transmitted to the exchange by the terminal station at the receiving end. The telephone numbers of all calling terminal stations, including those which are unable to set up a connection on the basis of the selection information, are transmitted to the terminal station at the receiving end, where they are stored and possibly displayed. A busy tone is signalled to the terminal stations calling unsuccessfully on the basis of the selection information, or the presence of selection information is explicitly indicated, for example in the form of a standard message.
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