What is the difference between SIP and SCCP?

• A. SIP is an IETF signaling protocol; SCCP is Cisco's proprietary endpoint control protocol.
• B. SIP is Cisco's proprietary protocol; SCCP is an IETF standard.
• C. Both are media transport protocols.
• D. SIP and SCCP are interchangeable.

Answer: (A)

The main idea is that SIP and SCCP serve the same general purpose—signaling for call setup and feature control—but they come from different origins and have different scope. SIP is defined by the IETF as a standard signaling protocol that endpoints use to initiate, modify, and terminate sessions. It’s text-based, vendor-neutral, and widely supported across many devices and platforms, which is why it’s used in diverse environments beyond Cisco. SCCP, also known as Skinny Client Control Protocol, is Cisco’s proprietary endpoint control protocol used primarily between Cisco IP phones and Cisco Unified Communications Manager. It handles similar functions—registration, call control, and feature signaling—but it’s not an open standard and is mainly intended for Cisco devices. The media itself isn’t carried by either signaling protocol; voice media typically flows over RTP once the session is established. So the correct view is that SIP is an IETF standard for signaling, while SCCP is Cisco’s proprietary signaling protocol for its own endpoints. The other statements aren’t accurate because signaling, not media transport, is the role here; SCCP isn’t an IETF standard, and the protocols aren’t interchangeable.