PURPOSE: To reduce number of constituent parts and eliminate restriction of packaging by multiplexing parallel output of whole ROM at once by a multiplexer and demultiplexing by a demultiplexer.

CONSTITUTION: Information made by digitalizing signals of speech service and various tones is written in ROM1-1∼1-n, and a control circuit 2 controls reading of ROM. A multiplexer 3 converts parallel signals read out from the ROM to serial signal according to control signals of the circuit 2 and multiplexes. Further, a demultiplexer 5 demultiplexes multiplexed signals outputted from the multiplexer 3 into serial signals corresponding to the ROM according to another control signal of the circuit 2.