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

# Transfer to number

> Prepare phone or SIP transfer destinations, conditions, and optional handoff settings without assuming telephony execution.

A transfer-to-number rule describes a handoff to a telephone or SIP destination. Confirm who operates that destination, when it is appropriate, and what the agent should say if the handoff cannot complete.

<Note>
  This guide covers configuration authoring. It does not provision a phone number, import a trunk, verify carrier support, or establish working transfers. Review [telephony availability](/agents-platform/deploy/telephony/overview) separately.
</Note>

## Prepare a rule

<Steps>
  <Step title="Review the destination">
    Obtain the intended phone number or SIP URI from its operator. Use approved test destinations in preparation materials; do not treat a syntactically valid value as proof it is reachable.
  </Step>

  <Step title="Open the tool editor">
    On the agent's **Tools > System tools** panel, enable **Transfer to Number**. Complete a transfer rule with a destination and a clear condition. The editor requires at least one complete rule before saving.
  </Step>

  <Step title="Review the transfer type">
    The contract accepts `blind`, `conference`, and `sip_refer`, with `conference` as the default. These describe requested transfer modes. Confirm the actual channel and destination support before planning execution.
  </Step>

  <Step title="Save the authored definition">
    **Save** updates the agent working copy. Preserve the reviewed definition in a complete [server draft](/agents-platform/deploy/versioning) and read back the rules. Keep connection and transfer testing pending.
  </Step>
</Steps>

## Destination and optional fields

The definition belongs at `conversation_config.agent.prompt.built_in_tools.transfer_to_number`. Set `params.system_tool_type` to `transfer_to_number`. Its `transfers` list contains `condition`, `transfer_destination`, and optional transfer settings.

| Destination `type` | Destination field |
| - | - |
| `phone` | `phone_number` |
| `sip_uri` | `sip_uri` |
| `phone_dynamic_variable` | `phone_number`, using the intended variable reference contract. |
| `sip_uri_dynamic_variable` | `sip_uri`, using the intended variable reference contract. |

The outer `params.enable_client_message` defaults to `true`. Each rule can also contain `custom_sip_headers`, `sip_refer_play_dialtone`, `uui`, and `post_dial_digits`. Review the exact [agent schema](/api-reference/agents-platform/get-agent) before supplying these fields. Do not assume they work on every carrier or transfer type.

Dynamic destinations require the same destination review as static ones. A caller-supplied value must not decide which destinations your service authorizes.

## Frequently asked questions

<AccordionGroup>
  <Accordion title="Does a saved number become a Threetone phone number?" id="faq-number-transfer-provisioning">
    No. It is a destination in an authored rule. Number ownership, provisioning, carrier configuration, and a supported call path are separate requirements.
  </Accordion>

  <Accordion title="Can I rely on a transfer message as success confirmation?" id="faq-number-transfer-result">
    No. Prepared wording is not a transfer result. Only a verified execution outcome can establish that a handoff completed.
  </Accordion>
</AccordionGroup>


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