ETSI TS 129 018-2001 数字蜂窝通信系统(第2+阶段).全球移动通信系统(UMTS).通用分组无线业务(GPRS).伺服GPRS支持节点(SGSN).访问者位置寄存器(VLR).Gs接口第3层规范3
Digital Cellular Telecommunications System (Phase 2+) (GSM); Universal Mobile Telecommunications System (UMTS); General Packet Radio Service (GPRS); Serving GPRS Support Node (SGSN) - Visitors Location Register (VLR); Gs Interface Layer 3 Specification 3