SIP 181 Call Is Being Forwarded vs 401 Unauthorized
SIP 181 (Call Is Being Forwarded) is a 1xx Provisional response, while 401 (Unauthorized) is a 4xx Client Failure response. 181 indicates that a proxy server may send this to indicate that the call is being forwarded to a different set of destinations. In contrast, 401 means that the request requires user authentication. The response includes a WWW-Authenticate header with a challenge for the realm.
Description
A proxy server may send this to indicate that the call is being forwarded to a different set of destinations.
Quand vous le voyez
When the callee has call forwarding enabled and the request is being redirected to another number or device.
Comment résoudre
No action needed. The call is being redirected. If forwarding is unintended, the callee should update their forwarding settings.
Description
The request requires user authentication. The response includes a WWW-Authenticate header with a challenge for the realm.
Quand vous le voyez
When making a request that requires Digest authentication. Common for REGISTER and INVITE requests to authenticated SIP trunks.
Comment résoudre
Resend the request with proper Authorization header containing valid credentials (Digest authentication).
Différences clés
181 is a 1xx Provisional response, while 401 is a 4xx Client Failure response.
SIP 181: A proxy server may send this to indicate that the call is being forwarded to a different set of destinations.
SIP 401: The request requires user authentication. The response includes a WWW-Authenticate header with a challenge for the realm.
You encounter 181 when when the callee has call forwarding enabled and the request is being redirected to another number or device.
You encounter 401 when when making a request that requires Digest authentication. Common for REGISTER and INVITE requests to authenticated SIP trunks.
Quand utiliser lequel
For 181 (Call Is Being Forwarded): No action needed. The call is being redirected. If forwarding is unintended, the callee should update their forwarding settings. For 401 (Unauthorized): Resend the request with proper Authorization header containing valid credentials (Digest authentication).