Retell AI Voice Agent + Twilio + Make.com — Inbound Lead Capture System for Service Company

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UPWORK JOB POSTING

Retell AI Voice Agent + Twilio SIP + Make.com — Full Lead Capture Pipeline

Prepared for: Dean Schilling | March 2026

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POSTING TITLE:

Retell AI Voice Agent + Twilio + Make.com — Inbound Lead Capture System for Service Company

JOB DESCRIPTION (Copy/Paste Into Upwork)

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I run an established construction services company (35 years, residential and commercial) and need a complete inbound lead capture system built using Retell AI, Twilio, and Make.com. This is not three separate projects — it's one integrated pipeline: AI voice agent answers the phone, captures lead data, and triggers automated workflows that notify my team and confirm with the caller.

I am not starting from scratch. I have prior experience with an AI inbound caller, have existing prompting and conversation flow documentation, and a nearly complete knowledge base ready to load. I need someone who can execute the technical buildout efficiently using what I've already prepared.

*** NON-NEGOTIABLE: All work must be built inside MY accounts — my Retell, my Twilio, my Make.com. I own every login, every configuration, every workflow. I need to duplicate, modify, and expand your work independently after this project. You build it, document it, hand it over. This is not optional. ***

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PHASE 1: Lead Capture Pipeline (Primary Deliverable)

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This is one integrated system — not separate pieces. The voice agent, telephony, and automation must work together from day one.

WHAT I'M PROVIDING:

• Existing conversation flow documentation and prompting from my previous AI caller setup

• Nearly complete knowledge base (company info, services, service area, FAQ responses)

• Active Twilio account with phone number

• Retell AI account access

• Make.com account access

• Exact data fields to capture — no guessing, no discovery needed

1. RETELL AI VOICE AGENT

Build the inbound voice agent using Retell's conversation flow builder. The agent's sole job is to capture lead information from every caller:

• Business name (if commercial)

• Contact name

• Phone number

• Email address

• Services they need

• Where they heard about us

• Site/project address(es)

The agent also answers common questions by pulling from the knowledge base I provide — services offered, service area, process overview. If a question falls outside the knowledge base, the agent lets the caller know someone will follow up.

2. TWILIO SIP INTEGRATION

Connect the Retell agent to my existing Twilio phone number via SIP trunk. Call routing:

• After-hours: calls go directly to AI agent

• Business hours: configurable — AI pickup or ring-through to office with AI as backup/overflow

3. MAKE.COM AUTOMATION WORKFLOWS

Make.com is the engine that turns captured data into action. Build the following scenarios:

Lead Notification Flow — Every completed call triggers a webhook from Retell. Make.com catches the data and instantly sends: email notification to my office manager with all captured lead info, and SMS notification with caller name, phone, and service requested.

Caller Confirmation Flow — Automated SMS and email sent to the caller after the call confirming the information captured. The message includes a direct email address for them to respond to our office manager if anything is incorrect or they have additional questions. This is the caller's first touchpoint after hanging up — it needs to feel professional and immediate.

Lead Logging — All captured lead data logged to a Google Sheet or simple database so nothing falls through the cracks and we can track volume, source, and conversion over time.

4. TESTING & REFINEMENT

Run test calls covering these scenarios and refine based on results:

• Standard residential estimate request

• Commercial inquiry with multiple service needs

• After-hours call

• Frustrated or confused caller

• Caller requesting services outside our scope

• Caller providing incomplete information

• Verify Make.com scenarios fire correctly for each call type

5. DOCUMENTATION & HANDOFF

This is critical. Deliver complete documentation for:

• Retell conversation flow logic — what each node does and why

• Twilio SIP configuration — how routing works and how to change it

• Make.com scenarios — step-by-step walkthrough of each workflow

• Knowledge base structure — how to update and add to it

• Troubleshooting guide — common issues and how to fix them

My office manager is learning Make.com. A 30–60 minute recorded training session walking her through the scenarios you built is required. She needs to understand how to maintain and expand these workflows without calling you back.

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PHASE 2: Zone-Based Site Visit Scheduling (Future Build)

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This is the next evolution of the system and will be a separate project after Phase 1 is proven. Including it here because it directly impacts who I hire — I want someone who can grow with this.

THE PROBLEM:

Right now, there's a 1–3 day gap between when a lead calls and when they get a site visit date. During that gap, they call other contractors. I hear "I never heard back so I went with someone else" even after our automated reply told them we'd be out within 1–2 weeks. That gap is costing us jobs.

THE SOLUTION:

Our crews hit specific cities on specific days every week. Zone-based scheduling means:

Geographic Matching — Caller provides their address. The system matches it to our service zone (city/ZIP lookup table) and identifies which day of the week we service that area.

Instant Scheduling — During the initial phone call, the AI agent offers the next available site visit date for that zone. "We have your area scheduled for Thursday the 12th — does morning or afternoon work better for you?"

Competitive Advantage — The caller gets a confirmed appointment before they hang up. They stop calling other contractors. We win the job on speed and follow-through alone.

This could be built as Make.com logic (address → zone lookup → next route day → calendar booking) or integrated directly into the Retell conversation flow. Open to your recommendation on the best approach.

If you have experience building geographic routing logic, calendar-based scheduling automation, or similar systems, mention it in your proposal. It tells me you can handle Phase 2 when we get there.

ABOUT THE BUSINESS:

• Established construction services company — 35 years in operation

• Full-service paving, pavement maintenance, and concrete

• Residential and commercial clients

• Western Wisconsin and Minneapolis metro service area

• Peak call volume: April through August

• Small team: owner, office manager, salesperson, field crews

• Currently using Twilio and Resend — adding Retell AI and Make.com to the stack

REQUIRED EXPERIENCE:

• Retell AI — Must have built and deployed at least one live voice agent. Show me proof. Non-negotiable.

• Twilio SIP — Must have connected Retell or similar voice AI to Twilio via SIP trunk.

• Make.com — Must have built webhook-triggered, multi-step automation scenarios. Not optional for this project.

• Conversation flow design — Multi-path call flows with branching logic and error handling.

• Webhook configuration — Comfortable pushing data between systems in real time.

• Builds in client accounts — Everything built in MY Retell, Twilio, and Make.com. No exceptions.

• Documentation — Complete handoff docs and recorded training session for my office manager.

PREFERRED (BONUS):

• Geographic routing or calendar-based scheduling automation experience (for Phase 2)

• Service business experience — trades, contractors, or home service companies

• Training ability — can teach a non-technical team member clearly and patiently

BUDGET & TIMELINE:

• Phase 1 (Retell + Twilio + Make.com): $1,000–$2,500 fixed price

• Timeline: Working system within 2 weeks of project start, including testing

• Training session with office manager within 1 week of delivery

• Phase 2 will be scoped and quoted separately once Phase 1 is proven

• If you deliver well, this becomes an ongoing relationship with future phases and optimization work

TO APPLY — Read This Carefully:

Generic proposals get rejected immediately. Your application must include:

• A Retell agent you've built — demo call recording, live agent link, or detailed case study. No Retell experience = no application.

• A Make.com scenario you've built that was triggered by a webhook. What did it do? What business problem did it solve?

• How you'd connect Retell to my existing Twilio number via SIP. Have you done this before? What issues did you hit?

• Confirmation that you'll build everything in my accounts and deliver full documentation plus a recorded training session.

• Your fixed price for Phase 1 and realistic timeline to deliver a testable system.

• If you have experience with geographic routing or scheduling automation, tell me about it.

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