Program Design Of Voip Based On PABX

Nowadays, IP voice call has become one of the mainstreams of the development of the communication technology. Via Internet telephone, people can communicate with each other freely. PABX (Private Automatic Branch Exchange) is widely applied in enterprise-leveled Telephone LAN. Through PABX switching device, users can converse with each other and talking with the users who have the Network Terminal is also available. Nevertheless, there still exists the shortcoming that the costs of hardware equipment and communication are too high. On the contrary, using the soft routers to realize the exchange function of PABX has an advantage of the low costs of the hardware equipment and communication. Therefore, about the enterprise-class IP telephone system which is combined with PABX and VOIP, the essay mainly studies how to realize the soft exchange between VOIP and PABX. Specific research content includes:First of all, analyze the key technology of VOIP which is related to the design of the soft exchange program that is involved in the essay, including VOIP frequency calculation, layered model analysis, audio packets and conversion module function analysis and the IP protocol and quality assurance analysis; Second, analyze the function of PABX5 which is related to the design of the soft exchange program that is involved in the essay, including public exchange service function, internal line function, exchange circuit relay function; Then, on the basis of the analysis to the key technology of VOIP and the function of PABX5, finish the design and implementation of the VOIP technology which is based on the soft exchange of PABX, including: PABX startup module, call processing module, PSTN calls initialization module, PSTN calls connection module, IP telephone call conversion module, cut off the modules and call end processing modules.This research may apply to the enterprise-leveled IP telephone system. It is able to unite the internal data network and voice network as one as well as adding, moving and changing from call control and call center to integrated voicemail and computer telephone, from caller identification to multiple, multilevel automatic operator and until the terminal telephone.