Browse categories
Explore
Fiverr Pro
English
$
USD
I will vapi cold calling ai agent prompt optimization, voice tuning, outbound error fix
Evan
About this gig
Are you trying to build an AI cold calling system that actually works, but keep running into transport errors, robotic AI voices, failed outbound calls, or broken automation?
I specialize in setting up, fixing, and optimizing AI cold calling systems using Vapi, Twilio, ElevenLabs, Supabase, and automation tools like Make.com and Zapier.
Whether you already have a setup that's broken or you're starting from scratch, I'll help you get your AI voice system running smoothly from end to end.
What You'll Get
- Fix Vapi + Twilio outbound calling issues
- Resolve Call.start.error get transport and routing problems
- Connect Twilio to Vapi
- Build AI cold calling agents that sound human
- Improve prompts for better conversation flow
- Add objection handling and gatekeeper logic
- Configure Script A/B switching based on lead data
- Set up appointment booking logic
- Capture and store customer information automatically
- Tune ElevenLabs voices for natural delivery
- Configure interruption handling
- Connect your system to Supabase, CRMs, or automation workflows
Tools: Vapi, Twilio, ElevenLabs, Supabase, Next.js, Make.com, Zapier
MESSAGE ME TO GET STARTED. I only take projects I know I can deliver successfully.
Get to know Evan
Evan
Secure OTP, 2FA, Twilio Flex Call Centers for SMS, WhatsApp And Email
- FromCanada
- Member sinceNov 2025
- Avg. response time2 hours
Languages
English
Hi, I’m Evan, an expert in Twilio Verify, OTP, 2FA, SMS, WhatsApp, Email Authentication, and Flex Call Center solutions.
I help SaaS apps, e-commerce platforms, and mobile apps secure user logins, implement multi-channel OTP, and build AI-powered call centers with Twilio Flex.
From IVR menus, call routing, and SIP trunks to CRM integration and n8n workflow automation, I deliver reliable, scalable, and fully tested solutions.
Let’s secure and automate your communication systems today!
FAQ
My Vapi calls are firing but never connecting or ringing. Can you fix that?
Yes, that's exactly what I specialise in. The most common cause is a broken connection between Vapi and Twilio at the transport or authentication level. I'll diagnose your exact setup, fix the routing issue, and test it until calls are properly connecting and ringing on real phone numbers.
My AI agent sounds robotic and keeps reading the script word for word. Can you make it sound more human?
Absolutely. I'll rewrite your prompt from scratch so the agent speaks naturally, adapts to the conversation, and doesn't sound like it's reading. I'll also add proper gatekeeper logic, objection handling, and a smooth booking flow so it performs like a real sales caller.
Can the agent handle different scripts based on the type of lead?
Yes. I can set up multi-script logic so the agent automatically switches between Script A and Script B based on the lead data passed into the call. For example, one script for businesses without a website and another for those with a weak website, both handled dynamically without manual input.
Can the agent capture customer details like name and phone number and save them to my database?
Yes. I can integrate a contact capture function directly into the agent so whenever the customer mentions their name or number during the call, the agent confirms it and automatically stores it back into your database like Supabase after the call ends.
What if I need help with the voice too, tone, pacing, and interruption handling?
That's covered in the Premium package. I'll select the best voice for cold calling, tune the stability, speed, and pacing using ElevenLabs, and configure interruption handling so the agent stops talking the moment the customer speaks. The goal is to make it sound as close to a real human caller as p
