> ## Documentation Index
> Fetch the complete documentation index at: https://documentation.uponai.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Debug Call Disconnection

> Look up disconnection reasons to diagnose why calls ended unexpectedly.

Check disconnection reasons via the **Call History** tab in the dashboard or the Get Call API.

<Note>
  Phone numbers that make many short calls in a short period may be marked as spam at the carrier level, causing calls to show up as `dial_failed`.
</Note>

## Disconnection Reasons

### Expected / Normal

| Reason                 | Call Status | Description                                             |
| ---------------------- | ----------- | ------------------------------------------------------- |
| `user_hangup`          | ended       | User hung up                                            |
| `agent_hangup`         | ended       | Agent hung up                                           |
| `call_transfer`        | ended       | Agent transferred the call                              |
| `voicemail_reached`    | ended       | Voicemail detected and agent is configured to handle it |
| `ivr_reached`          | ended       | IVR detected and agent is configured to hang up         |
| `inactivity`           | ended       | Call ended due to `end_call_after_silence_ms` threshold |
| `max_duration_reached` | ended       | Call ended due to maximum duration setting              |

### Not Connected

| Reason                                 | Description                                                                              |
| -------------------------------------- | ---------------------------------------------------------------------------------------- |
| `dial_busy`                            | Outbound call — number dialed is busy                                                    |
| `dial_failed`                          | Outbound call — dialing failed with no or unknown SIP error code                         |
| `dial_no_answer`                       | Outbound call — number didn't answer                                                     |
| `invalid_destination`                  | Number is invalid, has spaces/invalid characters, or wrong format (check E.164)          |
| `telephony_provider_permission_denied` | SIP trunk credentials not authenticated                                                  |
| `telephony_provider_unavailable`       | Telephony provider is down                                                               |
| `sip_routing_error`                    | SIP routing has too many hops or is in a loop                                            |
| `marked_as_spam`                       | Number marked as spam. See [Spam Likely Overview](/Deploy/call-pickup-rate/spam-likely). |
| `user_declined`                        | User declined the outbound call                                                          |

### Errors

| Reason                                | Description                                                                 |
| ------------------------------------- | --------------------------------------------------------------------------- |
| `concurrency_limit_reached`           | Concurrency limit hit — add retry with exponential backoff, or upgrade plan |
| `no_valid_payment`                    | No valid payment on file, or service shut down due to overdue bill          |
| `scam_detected`                       | Scam detected for that particular agent                                     |
| `error_llm_websocket_open`            | LLM websocket failed to open — check Custom LLM URL and server reachability |
| `error_llm_websocket_lost_connection` | LLM websocket dropped during the call                                       |
| `error_llm_websocket_runtime`         | LLM websocket received a non-1000 closing signal from your server           |
| `error_llm_websocket_corrupt_payload` | LLM websocket received unspecified payload                                  |
| `error_no_audio_received`             | No audio received from telephony or web frontend after connection           |
| `error_asr`                           | ASR encountered a problem                                                   |
| `error_retell`                        | Unspecified UponAI-side problem                                             |
| `error_unknown`                       | Unknown error                                                               |
| `error_user_not_joined`               | User didn't join web call within 30s of `startWebCall`                      |
| `registered_call_timeout`             | Phone call placed 5+ minutes after registration                             |