ETSI EN 301 347 V6.4.1 (1999-11) European Standard (Telecommunications series) Digital cellular telecommunications system (Phase 2+); General Packet Radio Service (GPRS); GPRS Tunnelling Protocol (GTP) across the Gn and Gp Interface; (GSM 09.60 version 6.4.1 Release 1997) GLOBAL SYSTEM FOR MOBILE COMMUNICATIONS R