When a warm_transfer target is classified as voicemail and Retell fails the transfer early, the transfer_call tool result is returned but the agent is never resumed on the caller’s leg. No LLM turn is generated, the node’s “Transfer failed” edge is never evaluated, and no TTS is produced. The caller hears on-hold music indefinitely until they hang up.
Agent agent_9016e2c142d7485c5e3de2239c
Call call_35b94200911574d9fec5e07b604
After transfer_call returns successful: false, the agent gets a turn on the caller’s leg, the “Transfer failed” edge is evaluated, and the flow transitions to the failure node where the agent speaks. The tool result itself instructs this: “Please inform the customer that the transfer did not go through…” The tool result lands in the transcript and the engine does nothing for the remaining 21 seconds.