Authentication information for each communication destination and communication condition information are stored so as to be associated with each other in accordance with each communication destination designated by a request accepted by a server apparatus. Communication permission information containing authentication information of the communication destination is accepted from a requester. Communication condition information associated with authentication information contained in the accepted communication permission information is acquired. Determination is made as to whether or not communication requested by the requester is consistent with a condition indicated by the acquired communication condition information. When determination is made that the communication requested by the requester is consistent with the condition indicated by the acquired communication condition information, the communication from the requester is relayed to the requested communication destination via a virtual service private line which is set in advance.