SIP 181 Call Is Being Forwarded vs 408 Request Timeout
SIP 181 (Call Is Being Forwarded) is a 1xx Provisional response, while 408 (Request Timeout) 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, 408 means that the server could not produce a response within a suitable time. The client may repeat the request without modifications at any later time.
Description
A proxy server may send this to indicate that the call is being forwarded to a different set of destinations.
When You See It
When the callee has call forwarding enabled and the request is being redirected to another number or device.
How to Fix
No action needed. The call is being redirected. If forwarding is unintended, the callee should update their forwarding settings.
Description
The server could not produce a response within a suitable time. The client may repeat the request without modifications at any later time.
When You See It
When the callee does not respond within the configured timeout (e.g., phone rings but is never answered, or the endpoint is unreachable).
How to Fix
Check if the callee's device is powered on and registered. Verify network connectivity. Consider adjusting the server's transaction timeout value.
Key Differences
181 is a 1xx Provisional response, while 408 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 408: The server could not produce a response within a suitable time. The client may repeat the request without modifications at any later time.
You encounter 181 when when the callee has call forwarding enabled and the request is being redirected to another number or device.
You encounter 408 when when the callee does not respond within the configured timeout (e.g., phone rings but is never answered, or the endpoint is unreachable).
When to Use Which
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 408 (Request Timeout): Check if the callee's device is powered on and registered. Verify network connectivity. Consider adjusting the server's transaction timeout value.