An IP telephone system includes a source IP telephone apparatus, a destination telephone apparatus, a Web server and an ENUM server. The IP telephone apparatuses function as base stations for multi-handset telephone systems and are connected to an IP network. The Web server stores ring tone information corresponding to a telephone number assigned to the source or destination IP telephone apparatus. The ENUM server stores a NAPTR resource record in which a URI specifies link data related to the ring tone information stored in the Web server. In the IP telephone system, the IP telephone apparatus that has received a call transmits, to the ENUM server, a query for a NAPTR record corresponding to an intended recipient's telephone number. The IP telephone apparatus then transmits, to the Web server, a request for the ring tone information corresponding to the intended recipient's telephone number according to the obtained NAPTR resource record, and sounds a ring tone through the apparatus itself and the handsets that are connected to the apparatus according to the obtained ring tone information.