### Answer Yes, you can use call transfer with a custom LLM agent. You trigger a transfer by including the

transfer_number

field in your response event sent back to Retell via the LLM WebSocket. [(1) ]() How to implement: In your response event, set the

transfer_number

field to the destination phone number:

javascript
const res = {
  response_type: "response",
  response_id: request.response_id,
  content: "Let me transfer you now.",
  content_complete: true,
  end_call: false,
  transfer_number: "+12137771234"
};
ws.send(JSON.stringify(res) ) ;

You can also use

agent_interrupt

to trigger an immediate transfer:

javascript
const res = {
  response_type: "agent_interrupt",
  content: "",
  content_complete: true,
  end_call: false,
  interrupt_id: 1,
  transfer_number: "+12162023041"
};

[(2) ]() Important limitations with custom LLM: - This performs a cold transfer (direct transfer without briefing the next agent) . [(3) ]() - Warm transfer with three-way bridging, hold music, and human detection are not available when using custom LLM. - Configuring the caller ID (showing the user's number vs. the agent's number) during transfer is not currently documented for custom LLM integrations. , [(2) ]()

​ To learn more, see the sources I considered: [[1] LLM WebSocket](https://docs.retellai.com/api-references/llm-websocket) [[2] User caller ID for call transfers when using custom LLM](https://discord.com/channels/1186424376300679209/1425072734785769472) [[3] Phone transfer with custom LLM](https://discord.com/channels/1186424376300679209/1395018119050952825) ​

Feel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.