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

# Single prompt vs. flow agent

> Voicy has two agent types. A single prompt agent runs a whole call from one set of instructions. A flow agent follows a visual map of steps that you design.

## Single prompt agents

You write one prompt that covers the agent's persona, goals and rules, and the agent follows it for the whole call. You can add a fixed welcome message and let the agent end the call when the caller is done. For most receptionist, FAQ and simple lead-capture agents, this is all you need.

Single prompt agents are the only type you can create and edit through the public API.

## Flow agents

You build the conversation on a canvas out of **nodes** (steps) connected by **transitions** (the conditions for moving between steps). Each node has its own job. One might talk with the caller, another collects details, calls your system or transfers the call. A global prompt holds the persona and shared rules, and every node uses it.

Use a flow agent when the call has to follow a set process. Examples are verifying details before an action, branching on what your CRM returns, sending an [SMS](/guides/sms) mid-call or handing the caller to a specific person.

## Comparison

| | Single prompt | Flow |
| - | - | - |
| How you build it | One prompt plus settings | Visual editor with nodes and transitions |
| Best for | Open conversations, FAQs, simple intake | Multi-step processes with branching |
| Collecting details during the call | Through the prompt; details you define are extracted after the call | Collection nodes that validate and store each answer as it's given |
| Calling your systems mid-call | No | Yes ([Function Call node](/guides/functions)) |
| SMS, transfer, outbound dial, lists | Can end the call | Yes, as dedicated nodes |
| [Knowledge bases](/guides/knowledge-base#markdown-file) | Yes | Yes |
| [Webhooks](/webhooks) and email summaries | Yes | Yes |
| Create or edit through the API | Yes | No. Build in the dashboard; the API can read it |
| Time to first test call | Minutes | Longer, depending on the flow |

<Tip>
  **How to choose.** Pick a single prompt agent when the call is an open conversation: answering questions, giving information, general support. Pick a flow agent when the call follows a fixed process: collecting and checking details, calling your systems, or routing the caller to the right place. If you start with a single prompt and later need a flow, your prompt is a good starting point for the flow's global prompt.
</Tip>

## Both types share

* The same voices, [pronunciation](/pronunciation-guide) overrides and speech-to-text vocabulary.
* Provided and extracted [variables](/guides/variables).
* A built-in call simulator for test calls from the browser.
* Versioning: you edit a draft, and phone calls only see your changes after you click **Deploy**.

Next: [Single prompt agents](/guides/single-prompt-agents) · [Flow agents](/guides/flow-agents) · [Writing a good prompt](/guides/writing-prompts)


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