SIP 300 Multiple Choices vs 421 Extension Required
SIP 300 (Multiple Choices) is a 3xx Redirection response, while 421 (Extension Required) is a 4xx Client Failure response. 300 indicates that the address in the request resolved to several choices, each with its own location. The user or UA can select a preferred communication endpoint. In contrast, 421 means that the UAS needs a particular extension to process the request but the extension is not listed in the Supported header.
Descrição
The address in the request resolved to several choices, each with its own location. The user or UA can select a preferred communication endpoint.
Quando você o vê
When a user has multiple registered devices or contact addresses and the server cannot determine which one to use.
Como corrigir
Select one of the provided Contact addresses and resend the request to that specific URI.
Descrição
The UAS needs a particular extension to process the request but the extension is not listed in the Supported header.
Quando você o vê
When the server requires a specific SIP extension that the client did not indicate support for.
Como corrigir
Add the required extension to the Supported header and ensure your UA implements it. Check the response for which extension is needed.
Diferenças principais
300 is a 3xx Redirection response, while 421 is a 4xx Client Failure response.
SIP 300: The address in the request resolved to several choices, each with its own location. The user or UA can select a preferred communication endpoint.
SIP 421: The UAS needs a particular extension to process the request but the extension is not listed in the Supported header.
You encounter 300 when when a user has multiple registered devices or contact addresses and the server cannot determine which one to use.
You encounter 421 when when the server requires a specific SIP extension that the client did not indicate support for.
Quando usar qual
For 300 (Multiple Choices): Select one of the provided Contact addresses and resend the request to that specific URI. For 421 (Extension Required): Add the required extension to the Supported header and ensure your UA implements it. Check the response for which extension is needed.