ETSI TS 101 298 Digital cellular telecommunications system (Phase 2+) (GSM); General Packet Radio Service (GPRS); Base Station System (BSS) - Serving GPRS Support Node (SGSN) interface; Gb interface Layer 1 (GSM 08.14 version 7.0.1 Release 1998)

standard by European Telecommunications Standards Institute, 08/01/1999