Patent ID: 8064468

Claim:
A method of performing register functions in an SIP load balancer, comprising the operations of: keeping an information table on which identifiers and network addresses of at least one real SIP server connected to a network; receiving a first register message from an user agent; copying the received first register message and transmitting the copied first register message to the at least one real SIP server recorded in the information table by referring to the information table; recording and keeping the identifiers of the at least one real SIP server to which the first register message is transmitted in connection with identification information of the user agent, wherein the identification information is one of a call ID of the user agent and an identifier of the user agent; receiving at least one response message in response to the first register message transmitted from the respective at least one real SIP server; reading the identification information and the identifiers of the real SIP server included in the response message and extracting an authentication character string included in the response message; recording the authentication character string in connection with the read identification information and the identifiers of the real SIP server in the information table; extracting header information with respect to authentication included in the at least one response message and generating an integration response message including the header information, wherein the header information includes an authentication character string; transmitting the integration response message to the user agent; receiving a first register response message in response to the integration response message from the user agent, wherein the first register response message includes an authentication response information in connection with the header information included in the integration response message; extracting the authentication response information included in the first register response message; reading identification information and the authentication character string included in the first register response message and searching identification information included in the first register response message by referring to the information table and a network address of the real SIP server in response to the authentication character string; transmitting a second response message including the extracted authentication response information to the retrieved network address of the real SIP server; receiving an acknowledgement message from the at least one real SIP server receiving the second register response message; and transmitting one of the received acknowledgement messages to the user agent.