Question: In an untrusted WLAN access scenario for IMS services over EPC, what additional information does IMS require to fulfill regulatory requirements, beyond the UE's local IP address?
Option 1: ePDG identity (IP address used in IKEv2 tunnel) and UE source port (TCP/UDP port)
Option 2: WLAN Access Point MAC Address and UE's IMSI
Option 3: P-GW IP Address and PDN ID
Option 4: S2b Interface Type and EPS Bearer ID
Explanation: To meet regulatory requirements in an untrusted WLAN access setup for IMS over EPC, additional to the UE's local IP address, IMS necessitates knowing the identity of the ePDG (which is the IP address utilized in establishing the IKEv2 tunnel) and the specific UE source port (whether TCP or UDP) used for setting up this tunnel with the ePDG. This ensures comprehensive tracking and compliance.