Question: What is the primary mechanism for negotiating the integrity algorithm between a User Equipment (UE) and a Proxy-Call Session Control Function (P-CSCF) for protecting SIP signaling in IP-based services?
Option 1: IMS AKA (Authentication and Key Agreement), which includes agreement on security associations and integrity keys.
Option 2: TLS (Transport Layer Security) protocol, ensuring confidentiality and integrity as mandated for SIP proxies.
Option 3: IPsec (Internet Protocol Security) mechanisms as outlined in Network Domain Security specifications.
Option 4: Manual Configuration by operators based on the Authentication Framework.
Explanation: The correct answer is Option 1 because IMS AKA negotiates the integrity algorithm between the UE and the P-CSCF for protecting SIP signaling, encompassing agreement on security associations and integrity keys. While TLS is an alternative for intra-domain or inter-network use, it's not highlighted as primary for this specific context. IPsec and Manual Configuration relate to broader network security aspects, not directly focused on negotiating integrity algorithms for SIP signaling between UE and P-CSCF.