INTERFACE UNIT BETWEEN DIGITAL CELLULAR PHONE AND PUBLIC NETWORK AND PUBLIC-NETWORK TELECOMMUNICATION METHOD USING THE UNIT

摘要

PURPOSE: An interface unit between a digital cellular phone and a public network, and a public-network telecommunication method using the unit, are provided to prevent a wire tap on a public telephone network, by using the interface unit in which a data frame processing function and a public-network connection function are included. CONSTITUTION: A Vocoder(202) codes the voice inputted via a microphone in order to generate compressed sound sources. The compressed sound sources are transmitted and received via an RF(Radio Frequency) modem(201). The interface unit includes a digital cellular phone connection port(204), a frame process part(206), a control processor(205), a modem chip-set(207) and a line interface part(208). A sound code is inputted via the cellular phone connection port(204) when a safe wired communication mode is selected. The sound code is processed by the frame process part(206) under the control of the control processor(205), and then is inputted into the modem chip-set(207). The modem chip-set(207) modulates an input signal, and then transmits it to a PSTN network(209) via the line interface part(208).