There is provided a server apparatus that realizes a suitable delivery service according to requests by performing a highly secure and easy-to-understand authentication while allowing anonymity to be maintained. During connection to the server apparatus, a communication terminal apparatus transmits an appliance type ID and a user ID to the server apparatus according to depression states of authentication buttons. The server apparatus receives the transmitted appliance type ID and user ID, determines the authentication level based on the received appliance type ID and user ID, selects a service content to be provided according to the determined authentication level, and transmits corresponding delivery data to the communication terminal apparatus. As a result, suitable data for requests from the user side can be delivered.