| 摘要 |
<p>When a calling subscriber number is transmitted from an exchange to a subscriber terminal in present telephone systems, the same signalling technique, i.e. either modem signalling or DTMF signalling, is always used. Because of this, the calling number delivery service can be used only by those subscriber terminals which use the same signalling technique as the exchange. The problem is solved by providing a special file in the exchange, the file containing the signalling parameters of different types of number display units, such as the signalling protocol, transmission moment and sequences of characters sent in different cases. When a call is being set up, the type of the display unit that the subscriber uses is read from the subscriber file, the parameters of the equipment are read from said special file, and the calling subscriber number is then transmitted using these parameters. It is thereby possible to connect equipment of any manufacturer to the exchange.</p> |
