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

# Inbound calls

> How calls reach your agent

An inbound call is a call placed **to** one of your imported Twilio numbers. The flow is automatic — once a number is imported, the agent answers.

## What happens on an inbound call

<Steps>
  <Step title="Caller dials your Twilio number">
    A real person picks up the phone and dials.
  </Step>

  <Step title="Twilio routes the call to Nixflex">
    Because the number's voice webhook points at our engine, Twilio opens a WebSocket and starts streaming audio.
  </Step>

  <Step title="Engine looks up the agent">
    The phone number record tells the engine which agent owns this call.
  </Step>

  <Step title="Agent says welcome message">
    The agent's `welcome_message` is spoken first.
  </Step>

  <Step title="Conversation runs">
    STT transcribes the caller, the LLM reasons, TTS speaks the reply. Interruptions, silence, and language changes are handled automatically.
  </Step>

  <Step title="Call ends">
    Either the caller hangs up, the agent says `[END_CALL]`, the silence timeout fires, or `max_call_duration_seconds` is hit.
  </Step>

  <Step title="Post-call processing">
    Recording is saved to Supabase storage. Post-call analysis runs (summary, sentiment, custom data extraction). Webhook fires if configured.
  </Step>
</Steps>

## Behaviour you get out of the box

You don't have to configure any of this — the engine handles it:

* **Barge-in / interruption** — caller can speak over the agent and the agent will stop
* **Silence handling** — if the caller goes quiet, the agent gently prompts after a few seconds
* **Language auto-detection** — backchannels and filler words match the caller's language
* **Voicemail detection** — if the call somehow lands on a voicemail, the engine hangs up cleanly (rare on inbound, but possible)
* **Call recording** — dual-channel recording stored on Nixflex; original stays on your Twilio account
* **Post-call analysis** — every call gets a summary and sentiment automatically

## History-aware behaviour

When an inbound call arrives, Nixflex looks up the caller's number in your past calls. If there are previous conversations, summaries are injected into the agent's prompt as background context.

The agent can naturally reference past interactions without you wiring up any database lookups:

> *Caller:* "Hi, it's Sarah."
> *Agent:* "Hi Sarah, welcome back. Last time you booked a check-up — were you calling to follow up on that, or is this something new?"

This works because the engine fetched Sarah's call history before the agent generated the first response.

## Reading the call back

After the call:

```bash theme={null}
# List recent calls
curl https://api.nixflex.com/v1/calls?limit=10 \
  -H "Authorization: Bearer KEY_ID:KEY_SECRET"

# Fetch one call with full transcript + recording URL
curl https://api.nixflex.com/v1/calls/CA1234567890 \
  -H "Authorization: Bearer KEY_ID:KEY_SECRET"
```

The call object includes:

* `transcript` — full conversation, both sides
* `recording_url` — permanent link to the audio file hosted on Nixflex
* `call_summary` — AI-written summary
* `caller_sentiment` — `happy`, `neutral`, or `frustrated`
* `call_successful` — boolean (did the agent achieve the goal)
* `extracted_data` — any custom fields you defined in post-call analysis

See [Get call](/api-reference/calls/get) for the full schema.