An Architecture and Design of IP Telephonly Gateway

摘要

IP telephony is a very attractive technology as voice/data integration over IP networks such as Internet/Intranet. This paper describes several techniques used in our IP telephony gateway prototype to improve performance and quality of voice. In the gateway, voice signal processing tasks such as voice compression are usually handled by DSP (Digital Signal Processing). A main CPU performs call control, protocol encapsulation, and voice packet forwarding between DSPs and LAN/WAN interface devices. In this case, the processing power of the CPU restricts system scalability, because the CPU should take all protocol tasks, manipulates and forwards all voice packets. An approach to design, high-performance and low-latency IP telephony gateway is presented, and the re-organization of DSP and DSP and CPU functionality utilizing a new high performance NEC DSP is proposed.