Signalling Connection Control Part (SCCP) subsystem numbers are used to identify applications within network entities which use SCCP signalling. GSM and UMTS SSNs In Global System for Mobile Communications (GSM) and Universal Mobile Telecommunications System (UMTS), subsystem numbers may be used between Public land mobile networks (PLMNs), in which case they are taken from the globally standardized range (1 - 31) or the part of the national network range (129 - 150) reserved for GSM/UMTS use between PLMNs. For use within a PLMN, numbers are taken from the part of the national network range (32 - 128 & 151 - 254) not reserved for GSM/UMTS use between PLMNs. The following globally standardized subsystem numbers have been allocated for use by GSM/UMTS: 0 Not used/Unknown 1 SCCP MG 6 HLR (MAP) 7 VLR (MAP) 8 MSC (MAP) 9 EIR (MAP) 10 is allocated for evolution (possible Authentication Centre). The following national network subsystem numbers have been allocated for use within GSM/UMTS networks: 249 PCAP 250 BSC (BSSAP-LE) 251 MSC (BSSAP-LE) 252 SMLC (BSSAP-LE) 253 BSS O&M (A interface) 254 BSSAP (A interface) The following national network subsystem numbers have been allocated for use within and between GSM/UMTS networks: 142 RANAP 143 RNSAP 145 GMLC (MAP) 146 CAP 147 gsmSCF (MAP) or IM-SSF (MAP) 148 SIWF (MAP) 149 SGSN (MAP) 150 GGSN (MAP) 241 INAP North American (ANSI) SSNs 232 CNAM (Calling Name) 247 LNP 248 800 number translation (AIN0.1) 254 800 number translation (TCAP) References CAP SCCP SSN reallocation (PDF) 3GPP TS 23.003 (HTML) Signaling System 7