TEA1098A is a speech and handsfree integrated circuit with low DC line voltage, voltage regulator with adjustable DC voltage, symmetrical high impedance inputs for dynamic, magnetic or electret microphones, DTMF input with confidence tone on earphone and/or loudspeaker, earphone amplifier for dynamic, magnetic or piezo-electric earpieces with externally adjustable gain, digital volume control on earphone amplifier, automatic gain control (AGC) for true line loss compensation, microphone mute, key tone mode. It provides a strong 3.35 V regulated supply for microcontroller or dialler, filtered power supply optimized according to line current, filtered 2.0 V power supply output for electret microphone, PD logic input for power-down. It also features asymmetrical high input impedance for electret microphone, loudspeaker amplifier with single-ended rail-to-rail output and externally adjustable gain, dynamic limiter on loudspeaker amplifier to prevent distortion, digital volume control on loudspeaker amplifier, and duplex controller consisting of signal and noise envelope monitors, decision logic, and voice.