Abstract: A high efficiency speech coding apparatus which can eliminate repetitions of high efficiency speech coding and decoding processes of a digital speech signal upon inter-office transit switching without employing a special exchange and a transit switching system which can prevent degradation in quality of speech information and increase in encode and decode processing delay upon transit switching are disclosed. The apparatus repetitively inserts a synchronizing signal into an output speech signal to an exchange and supervises an input speech signal from the exchange to detect a synchronizing signal in order to determine whether the destination of connection of the exchange is a subscriber line or another trunk circuit connected by way of another high efficiency coding apparatus.

Abstract: A speech signal coding system including a speech signal encoder for dividing received speech signals into a plurality of frames each having a predetermined time interval and for converting the speech signals into digital speech parameters. The system includes a multiplexer for multiplexing the output digital data from the speech signal encoder into a predetermined frame format; a control frame generator for generating, in response to an inputted facsimile signal, a control frame having speech data frame configuration for identifying a facsimile signal identification data indicating the input signal as the facsimile signal. A facsimile signal demodulator converts the facsimile signal into digital data and a bit-synchronous multiplexer multiplexes the digital data.