SIP 183 Session Progress vs 301 Moved Permanently
SIP 183 (Session Progress) is a 1xx Provisional response, while 301 (Moved Permanently) is a 3xx Redirection 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, 301 means that the user can no longer be found at the address in the Request-URI. The client should direct future requests to the new address in the Contact header.
Description
Used to convey information about the progress of the call that is not otherwise classified. Often carries early media (ringback tones, announcements) via SDP.
Quand vous le voyez
During call setup, especially in PSTN interworking scenarios. The response may contain SDP for early media like custom ringback tones or IVR prompts.
Comment résoudre
No fix needed — this is informational. If early media is not playing, check codec negotiation and SDP handling in your UA.
Description
The user can no longer be found at the address in the Request-URI. The client should direct future requests to the new address in the Contact header.
Quand vous le voyez
When a user has permanently changed their SIP address. All future calls should be directed to the new URI.
Comment résoudre
Update your address book or routing tables to use the new Contact URI provided in the response.
Différences clés
183 is a 1xx Provisional response, while 301 is a 3xx Redirection 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 301: The user can no longer be found at the address in the Request-URI. The client should direct future requests to the new address in the Contact header.
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 301 when when a user has permanently changed their SIP address. All future calls should be directed to the new URI.
Quand utiliser lequel
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 301 (Moved Permanently): Update your address book or routing tables to use the new Contact URI provided in the response.