SIP 100 Trying vs 501 Not Implemented
SIP 100 (Trying) is a 1xx Provisional response, while 501 (Not Implemented) is a 5xx Server Failure response. 100 indicates that the request has been received by the next-hop server and an unspecified action is being taken to process it. The UAC should expect additional responses. In contrast, 501 means that the server does not support the functionality required to fulfill the request. The method is recognized but not implemented.
Beschreibung
The request has been received by the next-hop server and an unspecified action is being taken to process it. The UAC should expect additional responses.
Wann Sie es sehen
Immediately after sending an INVITE. The proxy has received the call and is searching for the callee. This is the SIP equivalent of a dial tone.
Wie man es behebt
No fix needed — this is normal call setup behavior. If stuck on 100 Trying for too long, check network connectivity and proxy configuration.
Beschreibung
The server does not support the functionality required to fulfill the request. The method is recognized but not implemented.
Wann Sie es sehen
When the SIP method is valid but the server has not implemented it (e.g., INFO, UPDATE, PRACK on a basic server).
Wie man es behebt
Use a different method that the server supports. Check the Allow header in responses to see supported methods.
Wesentliche Unterschiede
100 is a 1xx Provisional response, while 501 is a 5xx Server Failure response.
SIP 100: The request has been received by the next-hop server and an unspecified action is being taken to process it. The UAC should expect additional responses.
SIP 501: The server does not support the functionality required to fulfill the request. The method is recognized but not implemented.
You encounter 100 when immediately after sending an INVITE. The proxy has received the call and is searching for the callee. This is the SIP equivalent of a dial tone.
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).
Wann welchen verwenden
For 100 (Trying): No fix needed — this is normal call setup behavior. If stuck on 100 Trying for too long, check network connectivity and proxy configuration. For 501 (Not Implemented): Use a different method that the server supports. Check the Allow header in responses to see supported methods.