Retell AI is using first principles to reimagine the call center with cutting-edge voice AI.
Thousands of companies use Retell's AI voice agents to handle sales, support, and logistics calls.
Backed by Y Combinator, Alt Capital, and other leading investors.
Scaled to $60M ARR with a team of 40 people, up from $5M at the start of 2025.
Top 50 AI app in a16z list, #4 on Brex's Fast-Growing Software Vendors of 2025, top ranking startup on Lean AI Leaderboard, Enterprise Tech 30.
Responsibilities
Manage and collaborate with customers to support complex SIP integrations with CCaaS/CPaaS platforms like NiCE, Five9, Avaya, Genesys, Amazon Connect, Twilio, and Telnyx
Investigate and debug call failures via PCAP analysis, SIP traces, and carrier logs to improve reliability
Act as the primary technical point of contact for enterprise clients post-onboarding
Translate customer technical feedback and friction points into actionable product improvements
Requirements
5+ years as a Telephony Engineer, VoIP Engineer, or equivalent low-latency networking role
Deep understanding of the SIP Protocol (RFC 3261), RTP (media) debugging voice quality issues with PCAPs