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.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. |
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 |