The invention discloses a network terminal audio internal and external network intercommunication system and method. The network terminal audio internal and external network intercommunication systemcomprises an internal and external security gateway, wherein the internal and external network security gateway is composed of an internal and external network separated signaling gateway SGW and an internal and external network separated media gateway MGW; the SGW is divided into an external network signaling gateway SGW-A and an internal network signaling gateway SGW-B; the MGWs are respectivelydeployed in an external network and an internal network; the SGW-A and the SGW-B cooperate to realize SIP signaling interaction; the MGWs are divided into an external network media gateway MGW-A andan MGW-B internal network media gateway which are respectively deployed in the external network and the internal network; and the MGW-A and the MGW-B realize real-time media stream intercommunicationthrough an E1 board card. According to the network terminal audio internal and external network intercommunication system, the external security gateway and the internal security gateway are deployedin the information intranet and the information extranet, and the innovative application of the information security isolation device is matched, so that the security access of the existing network signaling stream and media stream of the mobile internet terminal society is realized.