The K844P is a 4-channel 16-pin Phototransistor Output Optocoupler with AC input. It consist of a phototransistor optically coupled to 2 gallium arsenide infrared emitting diodes (reverse polarity). The elements are mounted on one lead-frame providing a fixed distance between input and output for highest safety requirements. It is suitable for answering machines, PBX and fax machines.