การพัฒนาเครื่องโทรศัพท์อินเทอรฺเนตต้นแบบที่ใช้โพรโทคอล SIP

Abstract

DEVELOPMENT OF INTERNET TELEPHONE USING SIP PROTOCOL

This research presents development of low cost internet telephone prototype by using 8051 family MCU AT89C51ED2, Ethernet controller RTL8019as, and PCM codec MC145480 as the main hardware and the software development be composed of user interface part, Ethernet chip interface part, voice data control part, and protocol ICMP, ARP, IP, UDP, RTP, and SIP supported part, which are main protocol for basic internet telephone. Testing is done by using SIP User Agent program and another developed internet telephone operating as remote UA and SCS SIP Proxy program operating as server. The prototype internet telephone can create session, cancel session, reject session, and terminate session on both of direct connection mode and operating with server mode, which are the basic function of internet telephone. In the voice part, prototype internet telephone can support PCM both of μ-law and A-law, which is basic voice codec for internet telephone. The development of low cost internet telephone prototype in this research can be a guideline for further development of low cost internet telephone for actual use.