SIP 301 Moved Permanently vs 400 Bad Request
SIP 301 (Moved Permanently) is a 3xx Redirection response, while 400 (Bad Request) is a 4xx Client 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, 400 means that the request could not be understood due to malformed syntax. The client should not repeat the request without modifications.
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 request could not be understood due to malformed syntax. The client should not repeat the request without modifications.
When You See It
When the SIP message has syntax errors, missing required headers, or invalid header values.
How to Fix
Review the SIP message for syntax errors. Check required headers (To, From, Call-ID, CSeq, Via, Max-Forwards) and ensure proper formatting.
Key Differences
301 is a 3xx Redirection response, while 400 is a 4xx Client 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 400: The request could not be understood due to malformed syntax. The client should not repeat the request without modifications.
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 400 when when the SIP message has syntax errors, missing required headers, or invalid header values.
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 400 (Bad Request): Review the SIP message for syntax errors. Check required headers (To, From, Call-ID, CSeq, Via, Max-Forwards) and ensure proper formatting.