SIP 100 Trying vs 489 Bad Event
SIP 100 (Trying) is a 1xx Provisional response, while 489 (Bad Event) is a 4xx Client 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, 489 means that the server did not understand the event package specified in the Event header of a SUBSCRIBE request.
Description
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.
Quand vous le voyez
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.
Comment résoudre
No fix needed — this is normal call setup behavior. If stuck on 100 Trying for too long, check network connectivity and proxy configuration.
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
100 is a 1xx Provisional response, while 489 is a 4xx Client 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 489: The server did not understand the event package specified in the Event header of a SUBSCRIBE request.
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 489 when when subscribing to an event package that the server does not support (e.g., dialog, presence, message-summary).
Quand utiliser lequel
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 489 (Bad Event): Check which event packages the server supports (OPTIONS request) and use a supported event package name.