Senior AI Automation Engineer Needed for Voice Agent + CRM System

I’m evaluating several approaches for an AI-powered lead handling system for a service business. The system should: Handle inbound calls using Vapi or Retell Answer common customer questions Qualify leads based on service, location, and urgency Book, reschedule, and cancel appointments Check Google Calendar availability Send confirmation/follow-up SMS Push lead and call information into a CRM Use n8n for workflow orchestration Handle API failures, unavailable times, and duplicate bookings Provide basic logging and error handling I am particularly interested in freelancers who have already built comparable systems rather than someone proposing a purely theoretical architecture. For your response, please include: A brief description of the closest system you have built. The architecture and tools you would use here. How you would prevent double bookings and inconsistent CRM/calendar data. How you would handle failed API calls or unavailable services. One relevant demo, portfolio item, or case study. Your estimated implementation timeline. Your fixed-price estimate for the complete implementation. I care more about practical experience and reliability than a long proposal. Skills AI Agent Development n8n Vapi Retell AI Twilio API Integration CRM Integration Google Calendar Webhooks Workflow Automation