Q. Which security mechanism protects SIP signaling between UE and P-CSCF?
a) TLS on port 5061
b) SSH
c) SRTP
d) IPsec ESP tunnels (IMS AKA derived keys)
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Correct answer: Letter d.
In IMS networks, SIP signaling between the UE and the P-CSCF is protected using IPsec ESP (Encapsulating Security Payload) tunnels.
- These tunnels use IMS AKA-derived keys for integrity and confidentiality.
- The protection includes authentication headers (AH) and/or encryption (ESP).
- This mechanism ensures that SIP messages are secure from eavesdropping or tampering during transport.
Q. Which security mechanism protects SIP signaling between UE and P-CSCF?
a) TLS on port 5061
→ Incorrect. TLS can secure SIP in other scenarios (like IBCF or between core IMS nodes), but not typically used between UE and P-CSCF.
b) SSH
→ Incorrect. SSH is not used in SIP/IMS for signaling protection.
c) SRTP
→ Incorrect. SRTP protects media (RTP), not signaling.
d) IPsec ESP tunnels (IMS AKA derived keys)
→ Correct. IPsec is the standard method to secure SIP signaling between UE and P-CSCF using IMS AKA-based keys. IMS mandates IPsec ESP between UE and P-CSCF to secure SIP.
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