Patent ID: 8583794

Claim:
A relay apparatus that is connected by way of a network to a server apparatus, with which address information of a user of a first terminal having an IP telephone function is registered, and relays communications of a second terminal and the first terminal with the network, the relay apparatus comprising: a first storage unit that stores an authentication ID used for authentication of a user of the second terminal and the address information of the user of the first terminal in association with each other; an authentication processing unit that receives from the second terminal an authentication message that includes the authentication ID and is used in the authentication of the user of the second terminal, and authenticates the user based on the received authentication message; a user address acquiring unit that acquires from the first storage unit the address information of the user of the first terminal corresponding to the authentication ID included in the authentication message, when the user of the second terminal is authenticated; and an address registering unit that sends a registration request of registering the acquired address information to the server apparatus as the address information of the user of the first terminal associated with the second terminal that transmits the authentication message.