Which of the following are recognized as SIP Headers?

The choice identifying "Contact" as a recognized SIP header is accurate because the Contact header is a standard component within the Session Initiation Protocol (SIP) framework. It is utilized to specify the URI of the user agent that is making the request or the endpoint that should be contacted for subsequent requests related to a session. This header plays a crucial role in session management, as it helps maintain the state and route messages correctly during SIP communications.

In contrast, while "Subject" is a header used in some communication protocols like email, it is not considered a standard SIP header. "Timestamp" is not a recognized SIP header either; it may relate to specific implementations or extensions, but it is not part of the foundational SIP specifications. Lastly, while "Body" refers to the payload of a SIP message, it is not categorized as a SIP header. The body may contain various forms of data, such as session descriptions, but headers are specifically defined fields that carry metadata, not the message content itself.