| 摘要 |
<p>A device for connection to a switched communication network to identify a calling subscriber (1) to a receiving subscriber (2) comprises a frequency generating device (36). The frequency generating device (36) generates a set of frequencies by which a calling subscriber (1) may be identified in response to connection between the calling subscriber (1) and receiving subscriber (2). The system may use monofrequencies on a chromatic scale capable of being generated by a human voice or DTMF frequencies. For DTMF frequencies the system may work automatically, semi-automatically by pressing a switch to activate the frequency generating assembly (36), or at fixed intervals.</p> |
