IP network audio system is audio, paging and voice alarm over internet system based on TCP/IP network transmission technology. It can work with any non-dedicated LAN and WAN network system. The complete system is composed by network sever (PC with software), network audio adapter and network paging microphone, so it will be much easier for installer and contractor to install or integrate over the existing network and low voltage system. The system is adapted high speed dual CPU processor (32 digit MCU and 16 digit DSP), digital amplifier to ensure less than 0.1 second delay and excellent frequency response 20-16K Hz. The system support various audio format for transmission includes Mp3, Mp2, AAC and WAV. The network audio system is of excellent compatible capacity with non-dedicated existing network system, and also supports external source player encoding. The network audio system is also have capacity to communicate across network gateway and router and switch, thus internet audio system is available. Moreover, voice evacuation system over network could be added. IP network audio system surpasses all strong points of traditional audio system, more advantageous features includes super long distance data transmission, easier and low cost maintenance, high capacity of two way interactive. The network audio system could be built-up over non-dedicated existing network system through one CAT5 or CAT6 cable, so a big amount of wiring cost could be saved, easier maintenance is also ensured. Each point could be distributed synchronized various programs from the server and end-user at terminal can interact with the server. This network communication protocol also enable the system could be easily integrated with CCTV, home automation, door access and fire fighting system.