When an operator of an Internet telephone inputs a telephone number, a server provides an IP address corresponding to the telephone number. Upon receiving the IP address and confirming a predetermined symbol in a host address portion of the IP address, the predetermined symbol is converted into a numeric value. Based on the converted IP address, a call destination is accessed. When the call destination is unavailable, the converted numeric value is incremented in order to generate another IP address. Then, the newly generated IP address is used to access another destination.