SIP 301 Moved Permanently vs 501 Not Implemented
SIP 301 (Moved Permanently) is a 3xx Redirection response, while 501 (Not Implemented) is a 5xx Server Failure response. 301 indicates that the user can no longer be found at the address in the Request-URI. The client should direct future requests to the new address in the Contact header. In contrast, 501 means that the server does not support the functionality required to fulfill the request. The method is recognized but not implemented.
Description
The user can no longer be found at the address in the Request-URI. The client should direct future requests to the new address in the Contact header.
When You See It
When a user has permanently changed their SIP address. All future calls should be directed to the new URI.
How to Fix
Update your address book or routing tables to use the new Contact URI provided in the response.
Description
The server does not support the functionality required to fulfill the request. The method is recognized but not implemented.
When You See It
When the SIP method is valid but the server has not implemented it (e.g., INFO, UPDATE, PRACK on a basic server).
How to Fix
Use a different method that the server supports. Check the Allow header in responses to see supported methods.
Key Differences
301 is a 3xx Redirection response, while 501 is a 5xx Server Failure response.
SIP 301: The user can no longer be found at the address in the Request-URI. The client should direct future requests to the new address in the Contact header.
SIP 501: The server does not support the functionality required to fulfill the request. The method is recognized but not implemented.
You encounter 301 when when a user has permanently changed their SIP address. All future calls should be directed to the new URI.
You encounter 501 when when the SIP method is valid but the server has not implemented it (e.g., INFO, UPDATE, PRACK on a basic server).
When to Use Which
For 301 (Moved Permanently): Update your address book or routing tables to use the new Contact URI provided in the response. For 501 (Not Implemented): Use a different method that the server supports. Check the Allow header in responses to see supported methods.