301 Moved Permanently

C.

The 301 response from the Web server should always include an alternative URL to which redirection should occur.

If it does, a Web browser will immediately retry the alternative URL.

So you never actually see a 301 error in a Web browser, unless perhaps you have a corrupt redirection chain e.g.

URL A redirects to URL B which in turn redirects back to URL A.

If your client is not a Web browser, it should behave in the same way as a Web browser i.e.

immediately retry the alternative URL.

The SIP (Session Initiation Protocol) is a signaling protocol used for initiating, maintaining, and terminating real-time sessions that involve video, voice, messaging, and other communications applications and services. The SIP protocol defines a set of responses to indicate the outcome of a SIP request sent by a user agent client (UAC) to a user agent server (UAS).

The SIP response 301 Moved Permanently belongs to the redirection response category. The redirection response category is used to indicate that the requested resource has been moved permanently or temporarily to a different location or address, and the UAC should try the new address in the subsequent requests.

Specifically, the 301 Moved Permanently response indicates that the requested resource has been moved to a new address permanently, and any future requests for the same resource should use the new URI provided in the response. This response is typically used when the requested resource has been moved to a different server or domain permanently, and the UAC needs to update its stored information about the location of the resource.

In contrast to the 3xx Redirection responses, the Provisional (1xx), Successful (2xx), Client Failure (4xx), and Server Failure (5xx) responses have different meanings and purposes.

• The Provisional response category (1xx) is used to indicate that the UAS has received the request, but the final response is not yet available. The UAC should continue to wait for the final response.
• The Successful response category (2xx) is used to indicate that the request was successful, and the UAS is sending a final response to the UAC.
• The Client Failure response category (4xx) is used to indicate that the request made by the UAC was not successful, and the UAC should modify the request and try again.
• The Server Failure response category (5xx) is used to indicate that the UAS encountered an error or could not fulfill the request made by the UAC.

In summary, the 301 Moved Permanently response belongs to the Redirection response category, which is used to indicate that the requested resource has been moved permanently or temporarily to a different location or address.