Interworking system between IP networks using different IP addressing scheme, application layer gateway (ALG), network address translator, and SIP message routing method thereof

摘要

Disclosed are an interworking system between IP networks using different IP addressing scheme, an application layer gateway (ALG), a network address translator, an interworking method, and a SIP message routing method. The interworking system between a local network using a private IP and a global network using a global IP includes a STUN server and an application layer gateway (ALG). The STUN server provides binding information of header information of a global IP binding request. The application layer gateway (ALG) performs a global IP binding request with header Information changed by IP masquerading, and performs routing by applying the received binding information to media receiving address information of a SIP message.