Implementation Of Voice/data Capability On The IXP425 Network Platform

In order to seamlessly and efficiently connect the heterogeneous network used in the home voice gateway such as H.323, SIP and PSTN which have different nature of transmission and agreement of communication, it is necessary to study and analysis signaling intercommunication on the basis of integrating the data and telephone services into a unified hardware platform.This project utilizes normal VOIP Softwares ( Linphone & OpenPhone ) , telephones ( SIP & H.323 ) and network packet interception tools (Etherealla, Hammerca) to intercept the network packet and analyze the call flow of SIP & H.323 signaling agreements in the MontaVista Linux embedded development environment of IntelIXP425 development board. At the same time, make a further analysis and design on the conversion between SIP-POTS and SIP-H.323 to find out a common signaling mechanism. The application layer uses opening source program such as H.323 Endpoint,SIP Proxy and ENUM Server to transfer the signaling. Store the fixed information of the signaling to reduce the transinformation and simplify the common signaling. Transmit the signaling data between programs with limited message queue. As SIP termination doesn't know the information from H.323 termination, it is necessary to analyze and modify the important SIP information such as method type, response code classes, from and to in the home gateway. Meanwhile, because RTP voice packet is transferred by home gateway, the terminations of both sides can't know the information from other side and the information could be IP address and communications port, RTP communications port and coding type which convert the IP address and its corresponding communications port with NAT server. The method above-mentioned solve the problems of signaling interconnect & compatibility of voice gateway and connection & conversion of telephone number and address. Solve the problem of voice media codec translation in the intercommunication between heterogeneous networks through converting G.711 or G.723 to the same compression coding with PCM by IXP400 & DSP format conversion Software. Put forward the solution of using inner common signaling to greatly reduce the complexity of telephone signaling integration, simplify the structure of system software and enhance the reliability of system by designing one to one conversion between two different telephone signaling, which can solve the problem of signaling interconnect & compatibility more easily and effectively. Furthermore, integrate the ENUM services and enable users to dial into a variety of telephone terminations on the basis of telephone numbers without changing the habits of dialing.Separately test the time from converting to establishing signaling PSTN-SIP,SIP-H.323 and PSTN-H.323 on the IntelIXP425 hardware platform, the time of signaling PSTN-SIP & PSTN-H.323 is from 4 to 7 seconds and the time of signaling SIP-H.323 is within 3 seconds. Because using the same invoice coding G.711 U-law and Intel IXP425 platform to process the invoice compression, the conversation clarity is increased greatly compared with the normal PC which uses audio card to process the invoice compression.