| 摘要 |
A key telephone terminal (T1) connected via a four-wire line (useful connection a, b and control connection c, d) to the exchange (VE) is also connected to a subscriber line (ATn), in addition to a data terminal (fax, PC). Since when a request for a connection comes from such a device, an indication occurs both on the useful connection and on the control connection but when a data terminal is connected, an indication only occurs on the useful connection (a, b wire), the system can tell whether a data communication or a normal communication exists. If a data communication is recognised, a temporary data protection is put into effect during the period of time of data transmission. Thus, the relevant subscriber connection is blocked for particular service features which can be activated by the system or by another subscriber (for example call insertion, call waiting and intrusion). Follow-up functions of manipulations at the key telephone terminal which are transmitted via the control connection are also suppressed during the existence of the temporary data protection. <IMAGE> |
