SIP 100 Trying vs 487 Request Terminated
SIP 100 (Trying) is a 1xx Provisional response, while 487 (Request Terminated) 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, 487 means that the request was terminated by a BYE or CANCEL. The original request was cancelled before it could be completed.
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 request was terminated by a BYE or CANCEL. The original request was cancelled before it could be completed.
Quand vous le voyez
When the caller hangs up before the callee answers (CANCEL sent for pending INVITE). This is normal call abandonment.
Comment résoudre
No fix needed — the caller intentionally terminated the request. This is normal behavior.
Différences clés
100 is a 1xx Provisional response, while 487 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 487: The request was terminated by a BYE or CANCEL. The original request was cancelled before it could be completed.
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 487 when when the caller hangs up before the callee answers (CANCEL sent for pending INVITE). This is normal call abandonment.
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 487 (Request Terminated): No fix needed — the caller intentionally terminated the request. This is normal behavior.