CTO / Technical Lead — AI Voice Agent, SIP Migration, Retell/Vapi at OneSeven Tech

Project Brief

A 210-person law firm is integrating an AI voice agent into their existing phone system to improve caller response times and automate routine interactions — like wire transfer verification — without adding headcount. The existing secretary-driven infrastructure stays in place; the AI layer works alongside it to handle volume and reduce wait times. This is a live production environment where reliability is non-negotiable and the integration must be seamless.

Must-Haves

• Hands-on PBX-to-SIP migration experience — has personally moved a live organization off a traditional POTS/PBX system onto a modern SIP trunk (Twilio, Telnyx, Sierra, or equivalent); can speak fluently to the physical-to-software boundary gotchas
• Phased rollout design — has built parallel SIP/legacy environments with incremental traffic shifting (1% → 5% → 25% → 100%) and rollback capability at every step
• Production voice AI experience — has shipped real-time voice agent stacks using Retell, Vapi, LiveKit, or equivalent; understands latency budgets, turn-taking, and interruption handling
• Privacy & compliance fluency — familiar with PII, financial data, attorney-client privilege, Retell BAA coverage, and data retention obligations for regulated environments
• Non-functional requirements as a first-class concern — treats observability, uptime SLOs, failover, and call quality monitoring as core deliverables, not afterthoughts
• Strong English communication — able to reassure non-technical stakeholders and run structured weekly demos for both the client and internal OST leadership

Nice to Have

• Prior experience deploying voice AI in law firms, financial services, or other regulated SMBs
• Familiarity with 3CX or similar mid-market PBX environments
• Background running forward-deployed engineering or managed services engagements
• Experience structuring milestone-based payment plans tied to phased delivery

What You Will Do

• Lead the full technical architecture and delivery of an AI voice agent system enhancing a live law firm phone infrastructure
• Design and execute a phased PBX-to-SIP migration with rollback controls at every stage, keeping the firm operational throughout
• Lead and coordinate a team of 2 OST engineers across the engagement for the MVP stage
• Run weekly demos and maintain accessible test endpoints so both OST leadership and the client can verify progress firsthand
• Define and own non-functional requirements: uptime, latency SLOs, observability, failover, and call quality monitoring
• Break down the full implementation scope into clear phases (Phase 1 / 2 / 3), each delivering standalone value, paired with milestone-based payment checkpoints
• Act as the primary technical voice with the client — translating complex infrastructure decisions into clear, confident guidance for non-technical stakeholders

Why This Could Be Your Next Big Move

• Replace critical infrastructure, not just ship a feature — this is a full PBX migration for a big law firm; the technical stakes are real and the impact is immediate
• Own the architecture end-to-end — you'll define the stack, the rollout plan, and the compliance posture; there's no existing playbook to follow
• Work at the intersection of voice AI and regulated infrastructure — a rare combination that puts you ahead of most AI engineers who've never touched live telecom
• Build something productizable — OST retains the IP, and the runbooks and patterns you create here become the foundation for future engagements

Benefits & Compensation

• 💵 $150 – $200/hour — paid in USD via bank transfer (US-based candidates) or Deel (LATAM-based candidates)
• 🌎 Fully Remote — must have strong understanding of US market and phone systems
• 📄 Freelance / Hourly contract — higher hours expected in the early project phases, tapering as the build stabilizes
• 🤝 Referral Program — earn a bonus for referring talent that gets hired

To Apply

Please send your resume in English.

Include the following:

• ✉️ Cover Letter — tell us about a voice AI integration you've shipped into a live production environment and how you managed rollback risk (required — applications without this will not be considered)
• 🔗 LinkedIn Profile URL (required)
• 💻 GitHub Repository (required)
• 📜 Certifications — if applicable (e.g. AWS, Twilio, telecom-related)

About OneSeven Tech

OneSeven Tech is an AI-enabled software agency headquartered in Miami, with 8 years building AI-driven digital products for scaling and established companies. We specialize in consulting, designing, and developing ROI-focused solutions across 22 industries — from healthcare and legal to real estate and fintech.
Our multidisciplinary team blends AI strategy, UX/UI, web and mobile engineering, and machine learning to deliver real outcomes. With 101+ successful projects completed and a 4.9/5 client rating, we work as a deeply embedded partner — not just a vendor. We operate as a remote-first organization with a global team and a US-based client portfolio.