I tried that too: { "type": "transferCall", "function": { "name": "transfer_call_tool", "parameters": { "type": "object", "properties": {}, "required": [] } }, "destinations": [ { "type": "number", "number": "+16474923594", "message": "Thank you for holding", "callerId": "+16474923594", "description": "When there is a request to speak to a human", "transferPlan": { "mode": "blind-transfer", "sipVerb": "dial" }, "numberE164CheckEnabled": true } ] }