SIP 181 Call Is Being Forwarded vs 501 Not Implemented
SIP 181 (Call Is Being Forwarded) is a 1xx Provisional response, while 501 (Not Implemented) is a 5xx Server Failure response. 181 indicates that a proxy server may send this to indicate that the call is being forwarded to a different set of destinations. In contrast, 501 means that the server does not support the functionality required to fulfill the request. The method is recognized but not implemented.
描述
A proxy server may send this to indicate that the call is being forwarded to a different set of destinations.
何时出现
When the callee has call forwarding enabled and the request is being redirected to another number or device.
如何修复
No action needed. The call is being redirected. If forwarding is unintended, the callee should update their forwarding settings.
描述
The server does not support the functionality required to fulfill the request. The method is recognized but not implemented.
何时出现
When the SIP method is valid but the server has not implemented it (e.g., INFO, UPDATE, PRACK on a basic server).
如何修复
Use a different method that the server supports. Check the Allow header in responses to see supported methods.
主要区别
181 is a 1xx Provisional response, while 501 is a 5xx Server Failure response.
SIP 181: A proxy server may send this to indicate that the call is being forwarded to a different set of destinations.
SIP 501: The server does not support the functionality required to fulfill the request. The method is recognized but not implemented.
You encounter 181 when when the callee has call forwarding enabled and the request is being redirected to another number or device.
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).
何时使用哪个
For 181 (Call Is Being Forwarded): No action needed. The call is being redirected. If forwarding is unintended, the callee should update their forwarding settings. For 501 (Not Implemented): Use a different method that the server supports. Check the Allow header in responses to see supported methods.