Abstract: The present invention relates to a system for providing information to a client terminal when conducting a communication service, and more particularly, to a system for providing information to at least one client terminal including an outgoing terminal and an incoming terminal when conducting a communication service, comprising: a call control and maintenance server for forming and maintaining a media session to conduct the communication service between the outgoing terminal and the incoming terminal; and an information maintenance server for maintaining the information to be transmitted to at least one client terminal, wherein the information maintenance server transmits to either the outgoing terminal or the incoming terminal information-related data, which is related to the information to be provided to the client terminal before the media session for the communication service between the outgoing terminal and the incoming terminal, or while the communication service is being conducted, and wherein the cl