SIP 180 Ringing vs 480 Temporarily Unavailable
SIP 180 (Ringing) is a 1xx Provisional response, while 480 (Temporarily Unavailable) is a 4xx Client Failure response. 180 indicates that the UA receiving the INVITE is trying to alert the user. This response is used to initiate local ringback tone at the caller's end. 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.
説明
The UA receiving the INVITE is trying to alert the user. This response is used to initiate local ringback tone at the caller's end.
このコードが表示される場合
During call setup when the callee's phone is ringing. You should hear a ringback tone after receiving this response.
解決方法
No fix needed — the callee's device is ringing. If the call never connects after ringing, check the callee's device or call forwarding settings.
説明
The callee's end system was contacted successfully but the callee is currently unavailable. The client may retry after some time.
このコードが表示される場合
When the user exists but is not currently reachable — phone is off, DND mode enabled, or all lines are busy.
解決方法
Try calling again later. Check if the callee has DND enabled or if their device is powered off. Configure voicemail for unavailable scenarios.
主な違い
180 is a 1xx Provisional response, while 480 is a 4xx Client Failure response.
SIP 180: The UA receiving the INVITE is trying to alert the user. This response is used to initiate local ringback tone at the caller's end.
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 180 when during call setup when the callee's phone is ringing. You should hear a ringback tone after receiving this response.
You encounter 480 when when the user exists but is not currently reachable — phone is off, DND mode enabled, or all lines are busy.
どちらをいつ使うか
For 180 (Ringing): No fix needed — the callee's device is ringing. If the call never connects after ringing, check the callee's device or call 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.