IP Telephony Proxy for LAN Terminal Transfer
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Solution Overview
Problem
Current IP telephony systems lack a method to transfer IP telephone communications between multiple IP telephone terminals within a local area network (LAN), relying on router-established correspondences between global and local IP addresses using NAT or IP masquerade techniques.
Innovation Solution
An IP telephony method utilizing a proxy and router to facilitate communication by generating records that map local IP addresses of caller terminals to global addresses of conversation partners, allowing IP packets to be routed through the proxy and then the router, enabling transfer between terminals within and outside the LAN.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a router establishes correspondence between global and local IP addresses using NAT or IP masquerade techniques, then single-terminal IP telephony connection is achieved, but multi-terminal communication transfer within LAN is not supported
Solution Approach 1:
The patent introduces a proxy server as an intermediary component between IP telephone terminals and the router. The proxy server maintains mapping records between local IP addresses of terminals and global IP addresses, and performs address translation for incoming calls. This intermediary enables multiple terminals to communicate through a single router connection while maintaining individual terminal identities, thus achieving multi-terminal capability without requiring each terminal to have direct router access.
2Adaptability or versatility
If one IP telephone terminal is connected to one router, then stable single-terminal connection is achieved, but communication transfer between multiple terminals is not possible
Solution Approach 1:
The proxy server is designed to handle multiple functions: it acts as a NAT device for address translation, maintains mapping records for multiple terminals, routes incoming calls to appropriate terminals, and enables transfer between terminals. This multi-functional design allows a single proxy server to support multiple terminals and various communication scenarios (direct calling, transfer, conference) without requiring separate infrastructure for each function.
Solution Approach 2:
The proxy server pre-establishes mapping records between local IP addresses of terminals and global IP addresses before communication occurs. When a terminal registers with the proxy server, the mapping relationship is created in advance. This preliminary setup enables the router and other terminals to immediately route calls to the correct terminal without requiring real-time discovery or complex negotiation during the call establishment phase.
Data Source
AI summary
An IP telephony method facilitating transferring an IP telephony communication inside a LAN is realized. A telephone conversation takes place between a first IP telephone terminal and a conversation partner's IP telephone terminal through a router and a proxy. The proxy relays the telephone conversation by referring to a proxy table that holds a correspondence among a global IP address and a receive port of the conversation partner's IP telephone terminal, and a local IP address and a receive port of the first IP telephone terminal during relay. To perform transfer from the first IP telephone terminal to a second IP telephone terminal, the local IP address and the receive port of the first IP telephone terminal in the proxy table are changed to a local IP address and a receive port of the second IP telephone terminal, respectively.