SIP 181 Call Is Being Forwarded vs 480 Temporarily Unavailable
SIP 181 (Call Is Being Forwarded) is a 1xx Provisional response, while 480 (Temporarily Unavailable) 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, 480 means that the callee's end system was contacted successfully but the callee is currently unavailable. The client may retry after some time.
Mô tả
A proxy server may send this to indicate that the call is being forwarded to a different set of destinations.
Khi bạn thấy mã này
When the callee has call forwarding enabled and the request is being redirected to another number or device.
Cách khắc phục
No action needed. The call is being redirected. If forwarding is unintended, the callee should update their forwarding settings.
Mô tả
The callee's end system was contacted successfully but the callee is currently unavailable. The client may retry after some time.
Khi bạn thấy mã này
When the user exists but is not currently reachable — phone is off, DND mode enabled, or all lines are busy.
Cách khắc phục
Try calling again later. Check if the callee has DND enabled or if their device is powered off. Configure voicemail for unavailable scenarios.
Sự khác biệt chính
181 is a 1xx Provisional response, while 480 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 480: The callee's end system was contacted successfully but the callee is currently unavailable. The client may retry after some 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 480 when when the user exists but is not currently reachable — phone is off, DND mode enabled, or all lines are busy.
Khi nào dùng cái nào
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 480 (Temporarily Unavailable): Try calling again later. Check if the callee has DND enabled or if their device is powered off. Configure voicemail for unavailable scenarios.