Vonage Voice API provides a failover strategy to ensure customer experience is maintained even in the event of technical issues with the primary server. The platform offers fallback URLs that can be set to secondary data centers or static JSON files, allowing for customizable failover scenarios using NCCO instructions. Configurable timeouts and WebSocket disconnection callbacks also enable proactive measures to prevent user disruptions. Additionally, signed callbacks using JWT can help protect against malicious requests, although this feature is still in the Developer Preview stage with some known limitations.