Which two options are two functions of a proxy CSCF? (Choose two.)
A. a SIP registrar that is responsible for session management
B. an entity in IMS that connects with the ENUM server for the number portability function
C. a SIP proxy node that acts as a signaling entry point into IMS
D. an entity in IMS that works on both signaling and bearer domain
E. an entity in IMS that connects with PCRF via the Rx interface
F. an entity in IMS that interacts with application servers
