SIP 180 Ringing vs 501 Not Implemented
SIP 180 (Ringing) is a 1xx Provisional response, while 501 (Not Implemented) is a 5xx Server Failure response. 180 indicates that the UA receiving the INVITE is trying to alert the user. This response is used to initiate local ringback tone at the caller's end. 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 UA receiving the INVITE is trying to alert the user. This response is used to initiate local ringback tone at the caller's end.
Quand vous le voyez
During call setup when the callee's phone is ringing. You should hear a ringback tone after receiving this response.
Comment résoudre
No fix needed — the callee's device is ringing. If the call never connects after ringing, check the callee's device or call forwarding settings.
Description
The server does not support the functionality required to fulfill the request. The method is recognized but not implemented.
Quand vous le voyez
When the SIP method is valid but the server has not implemented it (e.g., INFO, UPDATE, PRACK on a basic server).
Comment résoudre
Use a different method that the server supports. Check the Allow header in responses to see supported methods.
Différences clés
180 is a 1xx Provisional response, while 501 is a 5xx Server Failure response.
SIP 180: The UA receiving the INVITE is trying to alert the user. This response is used to initiate local ringback tone at the caller's end.
SIP 501: The server does not support the functionality required to fulfill the request. The method is recognized but not implemented.
You encounter 180 when during call setup when the callee's phone is ringing. You should hear a ringback tone after receiving this response.
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).
Quand utiliser lequel
For 180 (Ringing): No fix needed — the callee's device is ringing. If the call never connects after ringing, check the callee's device or call forwarding settings. For 501 (Not Implemented): Use a different method that the server supports. Check the Allow header in responses to see supported methods.