Lan-based Ip Telephony System Design

Internet Phone realizes the high-speed transmission and exchange of telephone subscriber's audio frequency dataflow by utilizing the existing computer network to make up the communication network of the telephone. Utilizing existing computer network resources to set up the communication system of the telephone opened up a new way for the telephone communication. It can save the telephone rate, It also saves a large amount installation cost of the telephone network, circuit fee, maintenance cost and project fee, etc. It can shorten the project cycle of installing, raise the utilization ratio of networks resource of the computer, suitable for the national conditions of our country. This system has extensive popularization and the prospect at the telephone communication of trade in educational system, scientific and technological system, electricity industry system, banking system, public security system, etc.The article introduces the conceptual scheme of the software design of this Inernet Phone based on LAN by combinating with the typical of the telephone communication and LAN. USB1. 1 communication protocal is adopted between the transmission of PC and telephone terminal. USB is flexible, stabile, PNP and high-speed(l2M/S), so it truly satisfied and realized the need of this system especially met the need of little audio data packet and high transmission speed. As we al 1 know,. UDP/IP protocal is used as the communication protocal between PC and PC. SQL-SERVER 2000 is based on ADO and is used to develop the C/S information base of IP user resource, by which the system can accomplish the need of the user. During the design, theidea of OOP predominates the whole process.Anymore , Multi-thread technicworks up the program and afforces the flexibility. With the extension ofcomputer and network ,IP (Internet Phone) will be used in more and morefields.