SIP 100 Trying vs 400 Bad Request
SIP 100 (Trying) is a 1xx Provisional response, while 400 (Bad Request) 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, 400 means that the request could not be understood due to malformed syntax. The client should not repeat the request without modifications.
Beschreibung
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.
Wann Sie es sehen
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.
Wie man es behebt
No fix needed — this is normal call setup behavior. If stuck on 100 Trying for too long, check network connectivity and proxy configuration.
Beschreibung
The request could not be understood due to malformed syntax. The client should not repeat the request without modifications.
Wann Sie es sehen
When the SIP message has syntax errors, missing required headers, or invalid header values.
Wie man es behebt
Review the SIP message for syntax errors. Check required headers (To, From, Call-ID, CSeq, Via, Max-Forwards) and ensure proper formatting.
Wesentliche Unterschiede
100 is a 1xx Provisional response, while 400 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 400: The request could not be understood due to malformed syntax. The client should not repeat the request without modifications.
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 400 when when the SIP message has syntax errors, missing required headers, or invalid header values.
Wann welchen verwenden
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 400 (Bad Request): Review the SIP message for syntax errors. Check required headers (To, From, Call-ID, CSeq, Via, Max-Forwards) and ensure proper formatting.