curl --request POST \
  --url http://localhost:8080/api/calls/{callId}/transfer \
  --header 'Content-Type: application/json' \
  --header 'X-API-KEY: <api-key>' \
  --header 'X-API-SECRET: <api-key>' \
  --data '
{
  "transfer_destination": {
    "type": "predefined",
    "number": "+14157778888"
  },
  "transfer_type": "warm_transfer",
  "public_handoff_option": {
    "type": "prompt",
    "prompt": "Please introduce the customer to the manager"
  },
  "metadata": {
    "reason": "Escalation to supervisor"
  }
}
'

{
  "message": "Call transfer initiated successfully",
  "status": "success",
  "error": null,
  "data": {
    "call_id": "call-123",
    "organization_id": "org-789",
    "transfer_id": "transfer_abc123",
    "current_status": "initiated"
  }
}