SIP 180 Ringing vs 400 Bad Request
SIP 180 (Ringing) is a 1xx Provisional response, while 400 (Bad Request) is a 4xx Client Failure response. 180 indicates that the UA receiving the INVITE is trying to alert the user. This response is used to initiate local ringback tone at the caller's end. In contrast, 400 means that the request could not be understood due to malformed syntax. The client should not repeat the request without modifications.
説明
The UA receiving the INVITE is trying to alert the user. This response is used to initiate local ringback tone at the caller's end.
このコードが表示される場合
During call setup when the callee's phone is ringing. You should hear a ringback tone after receiving this response.
解決方法
No fix needed — the callee's device is ringing. If the call never connects after ringing, check the callee's device or call forwarding settings.
説明
The request could not be understood due to malformed syntax. The client should not repeat the request without modifications.
このコードが表示される場合
When the SIP message has syntax errors, missing required headers, or invalid header values.
解決方法
Review the SIP message for syntax errors. Check required headers (To, From, Call-ID, CSeq, Via, Max-Forwards) and ensure proper formatting.
主な違い
180 is a 1xx Provisional response, while 400 is a 4xx Client Failure response.
SIP 180: The UA receiving the INVITE is trying to alert the user. This response is used to initiate local ringback tone at the caller's end.
SIP 400: The request could not be understood due to malformed syntax. The client should not repeat the request without modifications.
You encounter 180 when during call setup when the callee's phone is ringing. You should hear a ringback tone after receiving this response.
You encounter 400 when when the SIP message has syntax errors, missing required headers, or invalid header values.
どちらをいつ使うか
For 180 (Ringing): No fix needed — the callee's device is ringing. If the call never connects after ringing, check the callee's device or call forwarding settings. 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.