# Voice

Answer the client's phone line with an AI voice agent — bookings, lookups, handoff

> Full REST + WebSocket API reference: https://api.happ.tools/reference

Connect a SIP phone number and an AI voice agent answers the client's calls — greeting, natural conversation, tools, and human handoff.

<VoicePageDemo />

## Connect voice [#connect-voice]

1. [Set up a phone number](/docs/agents/phones) with SIP credentials (login, password, telephony URL).
2. Connect a [telephony provider](/docs/integrations/telephony) integration (Binotel, Ringostat, Phonet, Unitalk, Stream Telecom, or Custom Calls for anything else).
3. Assign an assistant configured for voice; optionally add [ElevenLabs](/docs/integrations/telephony#elevenlabs-premium-voices) for premium voices.
4. Call the number to test.

The agent can run [webhook tools](/docs/agents/tools) mid-call (bookings, lookups, CRM), trigger `webhook_postcall` follow-ups, and transfer to a human via the built-in `turnOffAiMode` tool. Calls are recorded and transcribed when the provider supports it.

## Settings [#settings]

| Setting                | Behavior                                                                                                                                         |
| ---------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------ |
| Eagerness: Eager       | Responds quickly, best for simple Q\&A                                                                                                           |
| Eagerness: Normal      | Balanced timing (default)                                                                                                                        |
| Eagerness: Patient     | Waits longer, best for complex questions                                                                                                         |
| Voice                  | Catalogue of provider voices — ElevenLabs, Deepgram, Gemini, OpenAI, xAI; hundreds of options, the exact list depends on the connected providers |
| Codec: A-law (default) | Standard international telephony, 8000 Hz                                                                                                        |
| Codec: μ-law           | Standard North American telephony, 8000 Hz                                                                                                       |

**API:** [api.happ.tools/reference](https://api.happ.tools/reference)

## Next [#next]

* [Set up a phone number](/docs/agents/phones) — SIP credentials
* [Telephony providers](/docs/integrations/telephony) — Binotel, Ringostat, Phonet, Unitalk, Stream Telecom, ElevenLabs
* [Configure tools](/docs/agents/tools) — actions during calls