> ## Documentation Index
> Fetch the complete documentation index at: https://docs.thinnest.ai/llms.txt
> Use this file to discover all available pages before exploring further.
# Node Types
> Reference for every Voice Workflow node — conversation, collector, condition, set variable, API request, transfer, end call, and global nodes.
# Node Types
Every Voice Workflow is built from **nodes**. Each node is one *phase* of the
call. At any moment only the **current** node's prompt and tools are active, which
is what keeps the agent on-script as the conversation moves from greet → branch →
collect → end.
Nodes fall into two families, plus a single terminal node:
They **own a caller turn** — the agent speaks, the caller replies, and the
[Director](/docs/voice/workflows/transitions) extracts variables from what was
said. **Conversation** and **Collector** nodes are conversational.
They **run instantly** with no caller turn. The flow passes straight through
them to the next conversational node. **Condition**, **Set Variable**, **API
Request**, **Knowledge**, **Tool**, and **Transfer** are internal.
A workflow always ends at a **Terminal** node — **End Call**.
In the [builder](/docs/voice/workflows/builder) the palette on the left groups
nodes exactly this way: **Conversational**, **Internal**, and **Terminal**.
## All node types
| Node | Family | What it does |
| ------------ | -------------- | ----------------------------------------------------------------------------------------------------------------- |
| Conversation | Conversational | Speaks using a per-node prompt layered over the Global Prompt; can extract and require variables this phase. |
| Collector | Conversational | A prebuilt, transcription-hardened collector for one common value (email, phone, name, address, or DTMF). |
| Condition | Internal | Branches by its outgoing **edge** conditions — no caller turn, no spoken output. |
| Set Variable | Internal | Sets a variable from a template string with `{{variable}}` interpolation. |
| API Request | Internal | Calls an external API (the unified API & Webhook tool) and maps response fields into variables. |
| Knowledge | Internal | Looks up a grounded answer from the agent's knowledge base and branches on whether it was found. |
| Tool | Internal | Runs one built-in integration (messaging, calendar, CRM…) and maps the result into variables. |
| Transfer | Internal | Bridges the live call to a human or phone number. |
| End Call | Terminal | Ends the call with an optional closing message and records an outcome label. |
| Global | Conversational | A Conversation node marked **Global** that any interruptible node can jump to, handle the situation, then return. |
These are **voice** workflow nodes. They are unrelated to the chat
[Flow Editor](/docs/workflows), which uses Agent / Tool / Team graph nodes.
## Conversation
The workhorse node. It speaks to the caller and drives the conversation forward.
| Setting | What it controls |
| -------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------- |
| **Prompt** | A per-node prompt that is layered **over** the shared [Global Prompt](/docs/voice/workflows/transitions). It governs only this phase of the call. |
| **First Message** | An optional opening line. Only the **opening** node greets the caller — set the First Message on your Start node. |
| **Extract** | The list of variables to capture from what the caller says during this phase. |
| **Require** | Variables that **must** be captured before the flow may leave this node. The node re-asks until they're filled. |
| **Model / Voice override** | Optionally run this single node on a different model or voice. |
| **Interruptible** | Whether [Global nodes](#global-nodes) are allowed to interrupt this node. |
**Extract** vs. **Require:** *extract* tells the Director which variables to listen
for this turn; *require* additionally blocks the transition until those variables
are captured. A variable can be extracted without being required.
## Collector
A **Collector** is a prebuilt, transcription-hardened node tuned to reliably
capture one common value over the phone, where spelled-out emails and digit
strings are easy to mishear.
Available collectors:
| Collector | Captures |
| --------- | ---------------------------- |
| Email | An email address. |
| Phone | A phone number. |
| Name | A caller's name. |
| Address | A postal address. |
| DTMF | Keypad digits (touch-tones). |
Reach for a Collector instead of a plain Conversation node whenever a phase exists
only to capture one of these values cleanly.
## Condition
An internal node that **routes** without speaking. It has a single output, and the
branching lives entirely on its outgoing **edges** — each edge carries its own
condition.
* **Equation edges** are checked first, deterministically, first-true-wins.
* An **Unconditional** edge acts as the "else".
Because a Condition node takes no caller turn, the flow passes straight through it
to the next conversational node. See
[Transitions, Variables & the Director](/docs/voice/workflows/transitions) for how
edge conditions are written and resolved.
A Condition node branches by **edge conditions**, not by true/false handles. To add
a branch, draw another edge from its output and give that edge a condition.
## Set Variable
An internal node that assigns a variable from a **template string**, with
`{{variable}}` interpolation so you can compose new values from existing ones — for
example setting `{{full_name}}` from `{{first_name}} {{last_name}}`. It runs
instantly and passes through to the next conversational node.
## API Request
An internal node that calls an external service and feeds the result back into the
workflow. It reuses the unified **API & Webhook** tool (`api_connect`), with three
modes — **API Endpoints**, **Webhook**, and **Free-form Request** — and a
**Response → Variable** mapping that lands response fields into workflow variables
so a downstream **Condition** can branch on them.
The chosen endpoint's parameters are filled from workflow variables of the same
name (extract-before-call), and on a failed call the node follows its **error
edge** so the call never hangs.
See [API Request Node](/docs/voice/workflows/api-request) for the full
configuration, including the Configure API modal, auth options, OpenAPI import, and
a worked example.
## Knowledge
An internal node that looks up a **grounded answer** from the agent's
[knowledge base](/docs/knowledge) at this exact step, stores the answer in a
variable, and lets the flow **branch on whether anything was found**. By default it
searches for the caller's latest message, so dropping a Knowledge node right after a
question "just works".
Unlike letting the agent decide on its own (which may answer from memory and get it
wrong), the Knowledge node makes the lookup **guaranteed and on-script** — and a
following Conversation node reads the stored answer back to the caller.
See [Knowledge Node](/docs/voice/workflows/knowledge) for configuration, the
found/not-found branching pattern, and a worked example.
## Tool
An internal node that runs **one built-in integration** — send an SMS, create a
calendar event, look up an order, push to a CRM — at this exact step, and maps the
result into variables. It uses the **same** tools you attach to an agent.
Where the **API Request** node calls *your own* APIs, the **Tool** node runs the
platform's built-in integrations. Like the agent deciding on its own, an agent
*might* call a tool — the Tool node makes the action **guaranteed** at the point you
place it.
See [Tool Node](/docs/voice/workflows/tool) for configuration, input/result
mapping, and a worked example.
## Transfer
An internal node that **bridges the live call** to a human agent or a phone number.
Use it when the caller needs a person, or when the workflow has done its job and the
rest of the call belongs to a human.
## End Call
The **terminal** node. Place it wherever a path through the workflow finishes.
| Setting | What it controls |
| ------------------- | ---------------------------------------------------------------------------------------------- |
| **Closing message** | An optional final line the agent says before hanging up. |
| **Outcome** | A label recorded for the run (e.g. `booked`, `not_interested`) so you can see how calls ended. |
Use distinct outcome labels on different End Call nodes to make your call results
easy to read after the fact.
## Global nodes
Any **Conversation** node can be marked **Global**. A Global node is not part of the
linear path — instead it has an **enter-condition** (a prompt or an equation) and
becomes reachable from **any interruptible node** the moment its enter-condition
matches.
This is how you handle things that can come up at any point in the call — a caller
raising a pricing objection, asking to speak to a human, or going off-script. When
the enter-condition matches:
1. The flow **jumps** to the Global node, which handles the situation.
2. When it's done, the flow **returns** to the node the caller was on.
A **cooldown** (measured in turns) prevents a Global node from re-triggering
immediately after it returns.
A node only reaches Globals if its **Interruptible** toggle is on. Turn it off on
nodes where an interruption would be disruptive (for example, mid-way through
collecting a sensitive value).
Global enter-conditions are written and evaluated like any other condition — see
[Transitions, Variables & the Director](/docs/voice/workflows/transitions) for the
resolution order (equation edges, then prompt edges, then global enter-conditions).
Keep each Conversation node focused: **one phase = one job**. A node that only
greets, or only confirms the appointment date, gives the Director a small, clear set
of variables to extract and edges to choose from — which makes routing more
accurate and the call faster.
## Next steps
How edges, conditions, variables, and the Director move the call between nodes.
Configure outbound API calls and map responses into variables.
Add, connect, and arrange nodes on the canvas.
Start from Lead Qualification, Appointment Booking, or Support Triage.