Most voice AI deployments expose sensitive data through public APIs. A developer shares how to lock it down: run VAPI agents on private infrastructure, route Twilio calls through your VPC, and validate webhook signatures server-side.

This setup keeps PII off third-party servers while maintaining sub-200ms latency. The trade-off: you manage infrastructure, but compliance becomes straightforward. Key steps include configuring VPC security groups for Twilio's IP ranges and implementing HMAC signature validation.

The solution handles real-time interruption detection and webhook authentication. Production deployments need session management, certificate validation, and proper error handling. Testing requires ngrok for local validation and monitoring for timeout issues.

Next steps involve implementing secret rotation every 90 days and configuring internal load balancers. Teams should also consider async webhook processing to avoid 5-second timeout failures during heavy database queries.