SIP 180 Ringing vs 199 Early Dialog Terminated
Both SIP 180 (Ringing) and 199 (Early Dialog Terminated) belong to the 1xx Provisional category. 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. Meanwhile, 199 means that a UAS can send this to indicate that an early dialog has been terminated. Used when forking results in multiple early dialogs.
Description
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.
Quand vous le voyez
During call setup when the callee's phone is ringing. You should hear a ringback tone after receiving this response.
Comment résoudre
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.
Description
A UAS can send this to indicate that an early dialog has been terminated. Used when forking results in multiple early dialogs.
Quand vous le voyez
In forked call scenarios when one of the forked branches is cancelled because another branch was answered.
Comment résoudre
No action needed. This is normal behavior in forked call setups. Ensure your UA handles early dialog termination gracefully.
Différences clés
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 199: A UAS can send this to indicate that an early dialog has been terminated. Used when forking results in multiple early dialogs.
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 199 when in forked call scenarios when one of the forked branches is cancelled because another branch was answered.
Quand utiliser lequel
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 199 (Early Dialog Terminated): No action needed. This is normal behavior in forked call setups. Ensure your UA handles early dialog termination gracefully.