Retell is building the new standard for automating call center communications, including sales, support, customer engagement, and retention calls.
Backed by Altman Capital, Y Combinator, and top investors, we've raised a $4.7M seed round and hit $14M ARR in 15 months.
Check us out on the Top Lean AI Native Companies Leaderboard at leanaileaderboard.com.
At Retell AI, we're not just automating calls—we’re transforming how the world communicates. Our AI voice agents are reshaping sales, support, and customer engagement for leading brands. Backed by Alt Capital, Y Combinator, and top-tier investors, we've raised $4.7M in seed funding and hit $14M ARR with just 12 people.
We’re one of the fastest-growing Voice AI startups and we're on a mission to become the standard for voice automation at scale. We're also one of the top-ranking startups at leanaileaderboard.com.
As a Founding Senior Telephony Engineer, you’ll own the foundation of our telephony stack, building the critical systems that connect our AI voice agents to the real world. From low-level SIP features to integrating with global carriers and CCaaS platforms, your work will directly impact call quality, reliability, and customer experience. You’ll move fast, collaborate with customers, and help define the gold standard for AI voice infrastructure.
Key Responsibilities
Online Assessment (30 min)
Phone Interviews
Onsite / Virtual Interviews (2–3 hrs)
fulltimeSan Carlos, CA, US$215K - $290K0.20% - 0.60%1+ years
contractRemote (US)$30K - $36K1+ years
fulltimeSan Carlos, CA, US$140K - $180K0.04% - 0.10%3+ years
internRemote (US)Brand/graphic designAny
fulltimeSan Carlos, CA, USFull stack$215K - $290K0.40% - 0.60%1+ years
fulltimeSan Carlos, CA, USFrontend$215K - $290K0.40% - 0.60%1+ years
fulltimeSan Carlos, CA, USFull cycle$185K - $215K0.05% - 0.15%3+ years
fulltimeSan Francisco Bay AreaFull stack$215K - $290K0.30% - 0.60%6+ years