Question: In a Trusted WLAN (TWAN) access to Evolved Packet Core (EPC) for IP Multimedia Subsystem (IMS) services, what entity is used as an IP anchor point, providing IP-Connectivity Access Network bearers via PDN connections and EPS bearers?
Option 1: P-GW (Packet Data Network Gateway)
Option 2: TWAG/TWAP (Trusted WLAN Access Gateway/Trusted WLAN Access Point)
Option 3: eNodeB (Evolved Node B)
Option 4: MME (Mobility Management Entity)
Explanation: In the context of IMS services over TWAN access to EPC, a P-GW serves as a crucial element by acting as an IP anchor point. This role is consistent across different access types, including TWAN, ensuring seamless IP connectivity through PDN connections and EPS bearers. The P-GW's function in this setup underscores its importance in managing subscriber sessions and providing the necessary IP connectivity for IMS services.