I think the issue is voicemail pickup counts as a successful answered transfer leg, so fallbackPlan never regains control. BUT after reading the docs, you probably want to explicitly enable voicemail detection on the assistant/call config side too — not just rely on transfer timeout. Vapi now has built-in voicemail detection: - provider: "vapi" (recommended) - google - openai - twilio So I’d test with something like: json "voicemailDetection": { "enabled": true, "provider": "vapi" } or Twilio AMD if carrier reliability matters. Feels like: - transfer technically succeeds - voicemail answers - timeout stops mattering - fallback never resumes So likely need voicemail detection + external callback/watchdog logic for reliable recovery in production.