41309401TH Rev.4 356 /8. EN9 and INU Circuit DiagramThe NCU board is selected from EN9 and INU because it differs depending on country’s specifica-tions.• EN9UK, Flance, EC countries• INUUS, Canada, Australia, New Zealand, Singapore, China, Malaysia,non-EC countries (Poland etc.)1. Block diagram• Figure A.33 shows a block diagram of EN9 circuit.• Figure A.34 shows a block diagram of INU circuit.2. General functions of this circuit are as follows:1) Generates and detects signals to be exchanged with a telephone exchange or network inPhases A defined by ITU T.30.• Loop formation for call origination• Line current detection (see note 1) before call origination• Dial tone detection (see note 1)• Generation of dial pulses (see note 2)• Busy tone detection (see note 1)• Ringing signal detection2) Sends various data and signals from the 46F/R46 board to the telephone line afteramplification.• Picture data/Protocol/Tonal signals/MF tone, etc.Note1: This procedure may be omitted depending on the dial parameters.2: MF (Multi-frequency) tone is generated by the modem and transferred to thetelephone line via the NCU board.
