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

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.

Salary: 150 - 200 USD Per hour

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