Security and Authentication Headers

Security and authentication are critical components of SIP communications to ensure that sessions are initiated, modified, and terminated by authenticated users and to safeguard the integrity and confidentiality of SIP messages. This section delves into the key SIP header fields related to security and authentication.

Proxy-Authenticate and WWW-Authenticate
These headers are used by servers to challenge a user agent for authentication. The WWW-Authenticate header is used in 401 (Unauthorized) and 407 (Proxy Authentication Required) responses to challenge the user agent directly, while Proxy-Authenticate is used by proxies to request credentials for accessing resources via the proxy.
Format Example: WWW-Authenticate: Digest realm="example.com", qop="auth", nonce="dcd98b7102dd2f0e8b11d0f600bfb0c093", opaque="5ccc069c403ebaf9f0171e9517f40e41"