SIP 183 Session Progress vs 604 Does Not Exist Anywhere
SIP 183 (Session Progress) is a 1xx Provisional response, while 604 (Does Not Exist Anywhere) is a 6xx Global Failure response. 183 indicates that used to convey information about the progress of the call that is not otherwise classified. Often carries early media (ringback tones, announcements) via SDP. In contrast, 604 means that the server has authoritative information that the user indicated in the Request-URI does not exist anywhere. Unlike 404, this is a definitive, global statement.
Beschreibung
Used to convey information about the progress of the call that is not otherwise classified. Often carries early media (ringback tones, announcements) via SDP.
Wann Sie es sehen
During call setup, especially in PSTN interworking scenarios. The response may contain SDP for early media like custom ringback tones or IVR prompts.
Wie man es behebt
No fix needed — this is informational. If early media is not playing, check codec negotiation and SDP handling in your UA.
Beschreibung
The server has authoritative information that the user indicated in the Request-URI does not exist anywhere. Unlike 404, this is a definitive, global statement.
Wann Sie es sehen
When the user definitively does not exist on any server in the network. The server has authoritative knowledge, not just local.
Wie man es behebt
The user does not exist. Verify the SIP URI or phone number. Unlike 404, retrying on other servers will not help.
Wesentliche Unterschiede
183 is a 1xx Provisional response, while 604 is a 6xx Global Failure response.
SIP 183: Used to convey information about the progress of the call that is not otherwise classified. Often carries early media (ringback tones, announcements) via SDP.
SIP 604: The server has authoritative information that the user indicated in the Request-URI does not exist anywhere. Unlike 404, this is a definitive, global statement.
You encounter 183 when during call setup, especially in PSTN interworking scenarios. The response may contain SDP for early media like custom ringback tones or IVR prompts.
You encounter 604 when when the user definitively does not exist on any server in the network. The server has authoritative knowledge, not just local.
Wann welchen verwenden
For 183 (Session Progress): No fix needed — this is informational. If early media is not playing, check codec negotiation and SDP handling in your UA. For 604 (Does Not Exist Anywhere): The user does not exist. Verify the SIP URI or phone number. Unlike 404, retrying on other servers will not help.