Network Elements Underlying Protocols CS A BSC, MSC BSSAP B/C/D/E/F/G HLR, VLR, EIR, SMSC, MSC, GMSC MAP Iu-CS RNC, MSC RANAP PSTN GMSC, MGW, Other PLMNs ISDNL3 Mc MSS, MGW H.248, SCTP, IP Nc MSS ISUP/BICC Nb MGW IP PS Iu-PS RNC, SGSN RANAP, GMM, SM,SMS Gb BSC, SGSN LLC, GMM,SM,SMS Gn SGSN, GGSN GTP Gp SGSN, Other PLMN (SGSN/GGSN) GTP Gr SGSN, HLR MAP