NOISE CANCELING METHOD FOR REMOVING NOISE WHEN SENDING OFFICE LINE DIAL FROM PRIVATE EXCHANGE

摘要

PURPOSE: A method for removing a noise when sending an office line dial from a private exchange is provided not to allow a user to listen to noise by blocking noise from being introduced to a subscriber circuit when a dial signal is sent. CONSTITUTION: A CPU(Central Processing Unit) checks whether an origination subscriber is hooked off(211). If the origination subscriber is hooked off, the CPU forms a speech path(212). When the first digit is inputted from a subscriber circuit by the origination subscriber(213), the CPU separates the origination subscriber circuit from a switching circuit(214). The CPU outputs the digit to a DTMF(Dual Tone Multi Frequency) transmitter(215). Applied digits are converted into a dial signal and send to a general telephone network(216). The CPU checks whether a final digit is applied(217). When the final digit is applied, the CPU sends a corresponding dial signal(218). The origination subscriber circuit and the switching circuit are connected for a communication service(219).