| 摘要 |
<p>This system can either replace or be coupled to the tone and ring generating equipment currently in use at telephone exchanges and is comprised of the following: input generating module, output generating module, modulating circuit, demodulating circuit, input interface, output interface, control circuit, RAM memory, mixing circuit and background music circuit. It uses the time periods normally assigned to the transmission of supervisory tones as well as other time periods during a telephone call also for transmitting spoken messages and background music concomitantly or not with the supervisory tones.</p> |
