SIP 181 Call Is Being Forwarded vs 487 Request Terminated
SIP 181 (Call Is Being Forwarded) is a 1xx Provisional response, while 487 (Request Terminated) is a 4xx Client 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, 487 means that the request was terminated by a BYE or CANCEL. The original request was cancelled before it could be completed.
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 request was terminated by a BYE or CANCEL. The original request was cancelled before it could be completed.
何时出现
When the caller hangs up before the callee answers (CANCEL sent for pending INVITE). This is normal call abandonment.
如何修复
No fix needed — the caller intentionally terminated the request. This is normal behavior.
主要区别
181 is a 1xx Provisional response, while 487 is a 4xx Client 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 487: The request was terminated by a BYE or CANCEL. The original request was cancelled before it could be completed.
You encounter 181 when when the callee has call forwarding enabled and the request is being redirected to another number or device.
You encounter 487 when when the caller hangs up before the callee answers (CANCEL sent for pending INVITE). This is normal call abandonment.
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 487 (Request Terminated): No fix needed — the caller intentionally terminated the request. This is normal behavior.