EPC stands for Evolved Packet Core. Also It is called the core network of LTE. the EPC is composed of following network elements: the Serving Gateway (Serving GW), the PDN Gateway (PDN GW), the MME, the HSS SGSN and PCRF. The EPC is connected to the external networks, which can include the IP Multimedia Core Network Subsystem (IMS).
Given below EPC nodes and their interfaces.