SIP 181 Call Is Being Forwarded vs 489 Bad Event
SIP 181 (Call Is Being Forwarded) is a 1xx Provisional response, while 489 (Bad Event) 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, 489 means that the server did not understand the event package specified in the Event header of a SUBSCRIBE request.
Description
A proxy server may send this to indicate that the call is being forwarded to a different set of destinations.
Quand vous le voyez
When the callee has call forwarding enabled and the request is being redirected to another number or device.
Comment résoudre
No action needed. The call is being redirected. If forwarding is unintended, the callee should update their forwarding settings.
Description
The server did not understand the event package specified in the Event header of a SUBSCRIBE request.
Quand vous le voyez
When subscribing to an event package that the server does not support (e.g., dialog, presence, message-summary).
Comment résoudre
Check which event packages the server supports (OPTIONS request) and use a supported event package name.
Différences clés
181 is a 1xx Provisional response, while 489 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 489: The server did not understand the event package specified in the Event header of a SUBSCRIBE request.
You encounter 181 when when the callee has call forwarding enabled and the request is being redirected to another number or device.
You encounter 489 when when subscribing to an event package that the server does not support (e.g., dialog, presence, message-summary).
Quand utiliser lequel
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 489 (Bad Event): Check which event packages the server supports (OPTIONS request) and use a supported event package name.