SIP 199 Early Dialog Terminated vs 485 Ambiguous
SIP 199 (Early Dialog Terminated) is a 1xx Provisional response, while 485 (Ambiguous) is a 4xx Client Failure response. 199 indicates that a UAS can send this to indicate that an early dialog has been terminated. Used when forking results in multiple early dialogs. In contrast, 485 means that the Request-URI was ambiguous. The response body may contain a list of possible unambiguous addresses.
Description
A UAS can send this to indicate that an early dialog has been terminated. Used when forking results in multiple early dialogs.
When You See It
In forked call scenarios when one of the forked branches is cancelled because another branch was answered.
How to Fix
No action needed. This is normal behavior in forked call setups. Ensure your UA handles early dialog termination gracefully.
Description
The Request-URI was ambiguous. The response body may contain a list of possible unambiguous addresses.
When You See It
When the destination address matches multiple users and the server cannot determine which one is intended.
How to Fix
Use a more specific SIP URI. Check the response body for a list of possible matches and select the correct one.
Key Differences
199 is a 1xx Provisional response, while 485 is a 4xx Client Failure response.
SIP 199: A UAS can send this to indicate that an early dialog has been terminated. Used when forking results in multiple early dialogs.
SIP 485: The Request-URI was ambiguous. The response body may contain a list of possible unambiguous addresses.
You encounter 199 when in forked call scenarios when one of the forked branches is cancelled because another branch was answered.
You encounter 485 when when the destination address matches multiple users and the server cannot determine which one is intended.
When to Use Which
For 199 (Early Dialog Terminated): No action needed. This is normal behavior in forked call setups. Ensure your UA handles early dialog termination gracefully. For 485 (Ambiguous): Use a more specific SIP URI. Check the response body for a list of possible matches and select the correct one.