3GPP TS 03.60 Service Description; Stage 2 (R97).
3GPP TS 4.08 Mobile Radio Interface Layer 3; Stage 3 (R97).
3GPP TS 9.60 GPRS Tunneling Protocol (GTP) Across the Gn and Gp Interface (R97).
3GPP TS 23.060 Service Description; Stage 2 (R99).
3GPP TS 24.008 Mobile Radio Interface Layer 3 Specification; Core Network Protocols-Stage 3 (R99)