ETSI PRETS 300 192-1991 用于电路交换呼叫控制并在终端设备和专用通讯网络间S参考点处的接口D信道信令第3层协议
Layer 3 Protocol for Signalling over the D- Channel of Interfaces at the S Reference Point between Terminal Equipment and Private Telecommunication Networks for the Control of Circuit-Switched Calls