ETSI GSM 09.06-1993 欧洲数字蜂窝通信系统(第2阶段).用于支持分组交换数据传输业务的PLMN与PSPDN/ISDN间的互通(ETSI ETS 300 603:1994)
European Digital Cellular Telecommunication System (Phase 2); Interworking between a PLMN and a PSPDN/ISDN for the Support of Packet Switched Data Transmission Services (ETSI ETS 300 603:1994)