TELEPHONE SYSTEM AND EQUIPMENT

PROBLEM TO BE SOLVED: To enable a user to easily utilize an IP network telephone by linking a telephone network and an IP network. SOLUTION: In call originating side telephone equipment 1, a call is originated to call incoming side telephone equipment 2 by using a telephone network 4, that call origination is stopped corresponding to a busy notice from a call incoming side, and a call is originated to the telephone equipment by using an IP network 3. In the telephone equipment 2, only when speaking with the telephone equipment 1 is enabled by using an IP network 5, corresponding to call incoming from the telephone equipment 1 using the telephone network 4, a state is transited into incoming wait from the telephone equipment 1 using the IP network 5. Corresponding to following operation for responding to call incoming from the telephone equipment 1 using the IP network 5, speaking is started with the telephone equipment 1 by using the IP network 5.