Which of the following does not belong to the characteristics of SIP protocol?

Question

Options

• AIP telephone signaling protocol
• BApplication layer protocol
• CThe protocol based on the text
• DTransport layer protocol

• A
  6% (1)
• B
  6% (1)
• C
  12% (2)
• D
  76% (13)

Explanation

D is correct because SIP (Session Initiation Protocol) operates at the Application Layer (Layer 7) of the OSI model, not the Transport Layer (Layer 4). SIP actually relies on transport layer protocols like UDP or TCP to carry its messages - it does not itself provide transport-layer services such as end-to-end delivery or port-to-port communication.

Options A, B, and C all accurately describe SIP: it is an IP telephony signaling protocol used to initiate, modify, and terminate multimedia sessions; it is an application-layer protocol, sitting above TCP/UDP just like HTTP or SMTP; and it is text-based, using human-readable messages structurally similar to HTTP requests and responses.

Memory tip: Think of SIP like HTTP for phone calls - HTTP is also text-based, application-layer, and rides on TCP. Nobody would call HTTP a "transport layer protocol," and the same logic applies to SIP. If a question asks whether SIP is a transport protocol, the answer is always no - SIP uses transport, it doesn't provide it.

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