Báo Cáo Study and apply sip protocol to implement a voip system for a medium-size enterprise network

ABSTRACT
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This article introduces the basic issues of SIP, one of point-point call signaling protocols in
the range of protocols for VoIP, from concept, position and role of SIP in a VoIP system to the
elements participating in a SIP call as well as the main operation of these elements. This article also
analyzes the core of this protocol like dialog and transaction as well as message’s structure. After
study the protocol in details, this article will present a design of an application system for transmitting
voice by PCs in networks of small and medium-size enterprises. With the program written by Visual
C++ 6.0 including main functionalities of SIP, and the processing of voice data in real-time, this
system is easy to implement and is highly applicable as well as extendable.

Keyworks: SIP, VoIP system using SIP, SIP_UAC, SIP_Proxy, SIP events.