SBC – Access front end node. It deals with access policies and media handling
CSCF – Signalling switching in IMS Core Nw. Does not handle media
HSS – Owner of registration data and triggers
ENUM – translator for E164 to IP
CPE – Access Router in customer’s premise
MGCF – Access Gateway for PLMN (MSS) handling signalling
MGW – Gateway for PLMN handling Media
MRF – IMS IVR for announcements and media bridging
TFTP – Device Configuration Manager
NPS – Network Presence Server