A sound element database is installed in an analog telephone hub. When hold operation or the like is performed on an analog telephone during voice communication, the analog telephone hub selectively reads out necessary sound element data from the sound element database, and sends the sound element data or the type information of the sound element data to an analog telephone on the held party side through a LAN. In an analog telephone hub on the held part side, an audible sound is generated on the basis of sound element data read out from the sound element database on the basis of the sent sound element data or the sound element data type information. This audible sound is supplied to the analog telephone on the held party side to be output. With this operation, an audible sound indicating the operation state of a communication terminal can be effectively transmitted to the communication terminal of the other party.