# Create a Voice AI Agent in Robylon

Create a voice AI agent, learn what every section of the voice agent builder controls, and attach the phone numbers it calls from.

> Source: https://www.robylon.ai/docs/voice/create-voice-agent
> Section: Voice

Create one from **Settings → Workflows & AI Agents → AI Agents**.

## How do I create a voice agent?

Click **Create AI Agent**, choose the **Voice** channel group, name the agent and create it.

<Steps>
  <Step title="Open AI Agents">
    Go to **Settings → Workflows & AI Agents → AI Agents** and click **Create AI Agent**.
  </Step>
  <Step title="Choose the channel group">
    Select **Voice** (Phone & voice calls) and click **Next**. Voice agents are always of type **Single Agent**.
  </Step>
  <Step title="Name the agent">
    Enter an **Agent Name** (required) and an **Agent Purpose**, a short description of what the agent does, such as "Calls customers whose order cannot be delivered and offers a refund or replacement".
  </Step>
  <Step title="Create it">
    Click **Create Agent**. The voice agent builder opens.
  </Step>
</Steps>

<Frame>
  <img src="/assets/docs/app-create-voice-agent.webp" alt="Create an AI Agent dialog with the Voice channel group selected" width="1008" height="829" />
</Frame>

<Frame>
  <img src="/assets/docs/app-voice-agent-builder.webp" alt="Voice agent builder with the system prompt on the left and functions, tools, providers, calling hours, timeouts and post-call settings on the right" width="2160" height="1350" />
</Frame>

## What can I configure in a voice agent?

The builder has the call's opening and the system prompt on the left, and a column of sections on the right. Each section has its own page:

| Section | What it controls | Read more |
| --- | --- | --- |
| **First Message Mode** and **First Message Field** | Who speaks first, and the opening line | [Call settings](https://www.robylon.ai/docs/voice/call-settings#how-does-the-call-start) |
| **System Prompt** | The agent's role, rules and conversation flow | [Prompt and tools](https://www.robylon.ai/docs/voice/prompt-and-tools) |
| **Functions** | Built-in actions such as ending the call, detecting voicemail or handing over to a person | [Prompt and tools](https://www.robylon.ai/docs/voice/prompt-and-tools#which-built-in-functions-can-a-voice-agent-use) |
| **Tools Available** | Your own tools, for example an API that looks up an order | [Prompt and tools](https://www.robylon.ai/docs/voice/prompt-and-tools#how-do-i-add-my-own-tools) |
| **User Info** | Details about the person being called, passed in as variables | [Prompt and tools](https://www.robylon.ai/docs/voice/prompt-and-tools#what-is-user-info) |
| **Set Call Triggers via API** | The endpoint and sample payload for starting calls | [Triggering calls](https://www.robylon.ai/docs/voice/triggering-calls) |
| **Voice Configurations** | The text to speech provider, voice and voice settings | [Text to speech](https://www.robylon.ai/docs/voice/text-to-speech) |
| **LLM Configuration** | The AI model and temperature | [LLM](https://www.robylon.ai/docs/voice/llm) |
| **Transcriber Settings** | The speech to text provider, language and listening settings | [Speech to text](https://www.robylon.ai/docs/voice/speech-to-text) |
| **Calling Hour Config** | When the agent may call | [Call settings](https://www.robylon.ai/docs/voice/call-settings#how-do-calling-hours-work) |
| **Call Timeout Settings** | What happens on silence, and the maximum call length | [Call settings](https://www.robylon.ai/docs/voice/call-settings#what-happens-when-the-caller-goes-silent) |
| **Post Call Analysis** | Values to extract from each call, or a workflow to run afterwards | [Post-call analysis](https://www.robylon.ai/docs/voice/post-call-analysis) |
| **Call Success Evaluation** | How Robylon decides whether a call succeeded | [Post-call analysis](https://www.robylon.ai/docs/voice/post-call-analysis#how-does-call-success-evaluation-work) |

The header has **Test Call** and **Test Chat** for trying the agent ([Testing](https://www.robylon.ai/docs/voice/testing)), a version history button, and the controls to edit, publish and pause the agent. Changes are made on a draft and go live when you publish. See [Version history](https://www.robylon.ai/docs/ai-agents/version-history).

## How do I attach phone numbers to a voice agent?

In the voice agent builder, click **Add a Calling Number**. Choose the call direction in **Select phone number type** (**Inbound** or **Outbound**), then pick numbers under **Phone Numbers** from the ones added in **Settings → Channels → Voice**, and click **Save**. Only numbers set to be used by **AI** can be attached.

- **Outbound:** you can attach several numbers. When the agent places a call, Robylon picks one of the attached numbers that has not already been tried for that call request.
- **Inbound:** you can attach a single number. Answering incoming calls on a number with a voice agent is switched on by the Robylon team: it is available on request, email support@robylon.ai.

<Frame>
  <img src="/assets/docs/app-voice-calling-number.webp" alt="Add a Calling Number dialog with Select phone number type and Phone Numbers" width="426" height="235" />
</Frame>

## Which defaults does a new voice agent start with?

A new agent starts with working defaults, so you can test it before tuning anything:

| Setting | Default |
| --- | --- |
| First message mode | Assistant speaks first with model generated message |
| Speech to text | Deepgram, model Nova 2, English |
| Text to speech | ElevenLabs, model Eleven Flash v2.5, voice Anika - Customer Care Agent |
| Temperature | 0 |
| Silence timeout | 60 seconds |
| Maximum duration | 200 seconds |

Pick the AI model yourself in **LLM Configuration**. If no model can be loaded for a call, the call uses Gemini Flash 2.5.

## What makes a good first voice agent?

Start narrow. Pick one call type with a clear goal, such as confirming a delivery address or reminding a customer about a payment, and build that first. A focused agent is easier to prompt, test and measure than one that tries to handle every kind of call.